Novel benzimidazole derivatives

ABSTRACT

This invention provides compounds having the structure:  
                 
 
     wherein each of R 1 , R 2 , R 3  and R 9  is independently H; straight chain or branched, substituted or unsubstituted C 1 -C 7  alkyl, C 2 -C 7  alkenyl or alkynyl; C 3 -C 7  cycloalkyl or cycloalkenyl; acyl, phenyl, substituted phenyl, or heteroaryl; wherein each dashed line represents a single bond or a double bond with the proviso that if R 1  is present, R 3  is absent and there is a double bond between N at position 3 and C at position 2 and a single bond between C at position 2 and N at position 1 and if R 3  is present, R 1  is absent and there is a double bond between N at position 1 and C at position 2 and a single bond between C at position 2 and N at position 3; wherein each of R 4 , R 5  and R 6  is independently H, F, Cl, Br, I; straight chain or branched, substituted or unsubstituted C 1 -C 7  alkyl, C 2 -C 7  alkenyl or alkynyl; C 3 -C 7  cycloalkyl or cycloalkenyl; phenyl, substituted phenyl, heteroaryl, —OH, —OR 7 , —CN, —COR 7 , —CO 2 R 7 , —CON(R 7 ) 2 , —OCOR 7 , —SR 7 , —N(R 7 ) 2 , —NR 7 COR 7 , —(CH 2 ) n OR 7 , —(CH 2 ) n N(R 7 ) 2 , —(CH 2 ) n NR 7 COR 7 , wherein n is an integer from 1 to 4; and wherein each of R 7  and R 8  is independently H; straight chain or branched, substituted or unsubstituted C 1 -C 7  alkyl, C 2 -C 7  alkenyl or alkynyl; phenyl or substituted phenyl.  
     These compounds are selective for cloned human alpha 2 receptors and are useful as analgesic, sedative or anaesthetic agents.

BACKGROUND OF THE INVENTION

[0001] This application is a continuation-in-part of U.S. Ser. No.08/285,956 filed Aug. 4, 1994, the contents of which are incorporated byreference.

[0002] Throughout this application, various references are referred towithin parentheses. Disclosure of these publications in their entiretiesare hereby incorporated by reference into this application to more fullydescribe the state of the art to which this invention pertains.

[0003] Alpha adrenergic receptors are plasma membrane receptors whichare located in the peripheral and central nervous systems throughout thebody. They are members of a diverse family of structurally relatedreceptors which contain seven putative helical domains and transducesignals by coupling to guanine nucleotide binding proteins (G-proteins).These receptors are important for controlling many physiologicalfunctions and, thus, have been important targets for drug developmentduring the past 40 years. Examples of alpha adrenergic drugs includeclonidine, phenoxybenzamine and prazosin (for treatment ofhypertension), naphazoline (for nasal decongestion), medetomidine (forveterinary analgesia), UK-14,304 and p-aminoclonidine (for glaucoma)However, most of these drugs produce undesirable side effects which maybe due to the their interactions with other receptor subtypes. Forexample, clonidine is a well known centrally acting antihypertensiveagent. However, it also produces untoward side effects such asanalgesia, sedation, bradycardia and dry mouth which may be due to itslack of selectivity for a specific receptor subtype, i.e. α₂ receptor.

[0004] Alpha adrenoceptors were originally proposed to have onlytwo(alpha and beta) subtypes (Berthelsen, S.; Pethinger W. Life Sci.1977, 21, 595). However, modern molecular biological and pharmacologicaltechniques have led to the identification of at least 6 subtypes(α_(1a), α_(1b), α_(1c), α_(2a), α_(2b) and α_(2c)) of the adrenoceptors(Bylund, D. B., Trends Pharmacol. Sci. 1988, 9, 356; Weinshank et al,U.S. Pat. No. 5,053,337, issued Oct. 1, 1991; Bard et al, InternationalPublication No. WO 94/08040, published Apr. 14, 1994).

[0005] Among many other therapeutic indications, α₂ receptors arebelieved to modulate pain- and behavioral depression by regulating locuscoeruleus firing. In addition, α₂ receptors are well known to beinvolved in effects on blood pressure, heart rate, vasoconstriction andglaucoma. However, it is not known which therapeutic indications arecontrolled by each of these subtypes.

[0006] The effects of alpha-2 receptor agonists on analgesia, anesthesiaand sedation have been well documented for past 10 years (Pertovaara,A., Progress in Neurobiology, 1993, 40, 691). For example, systematicadministration of clonidine has been shown to produce antinociception invarious species including human patients in addition to its well knownsedative effects. Intrathecal and epidural administration of clonidinehas also proved effective in producing antinociception. Another alpha-2agonist, Medetomidine, which has better alpha-2/alpha-1 selectivity andis more potent at alpha-2 receptors than clonidine, has been extensivelystudied for its antinociception effect. In the spinally-initiatedheat-induced tail flick test in rats, systematic administration ofmedetomidine produced a dose-dependent antinociception which could betotally reversed by alpha-2 receptor antagonists, atipamazole oridazoxan. Experimental studies of medetomidine on pain sensitivity inhumans also indicated that this agent is very effective on ischemicpains, even though effective drug doses were high enough to produce asedation and considerable decrease in blood pressure.

[0007] Effects of alpha-2 receptor agonists in anaesthetic practice havealso been investigated. The sedative effect of alpha-2 agonists isregarded as good component of premedication. Another beneficial effectof alpha-2 agonists in anaesthetic practice is their ability topotentiate the anaesthetic action of other agents and to reduceanaesthetic requirements of other drugs during surgery. Studies showsthat premedication with 5 μg kg⁻¹ of oral clonidine administrationreduced fentanyl requirements for induction and intubation by 45% inpatient undergoing aortocoronary bypass surgery (Ghingnone, M, et al,Anesthesiology 1986, 64, 36).

[0008] This invention is directed to novel benzimidazole derivativeswhich are selective for cloned human alpha 2 receptors. This inventionis also related to uses of these compounds as analgesic, sedative andanaesthetic agents. In addition, this invention includes using suchcompounds for lowering intraocular pressure, and treatment of migraine,hypertension, alcohol withdrawal, drug addiction, rheumatoid arthritis,ischemia, spasticity, diarrhea, nasal decongestion. Furthermore thecompounds may be useful as cognition enhancers.

SUMMARY OF THE INVENTION

[0009] This invention provides compounds having the structure:

[0010] wherein each of R₁, R₂, R₃ and R₉ is independently H; straightchain or branched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl,substituted phenyl, or heteroaryl; wherein each dashed line represents asingle bond or a double bond with the proviso that if R₁ is present, R₃is absent and there is a double bond between N at position 3 and C atposition 2 and a single bond between C at position 2 and N at position 1and if R₃ is present, R₁ is absent and there is a double bond between Nat position 1 and C at position 2 and a single bond between C atposition 2 and N at position 3; wherein each of R₄, R₁ and R₆ isindependently H, F, Cl, Br, I; straight chain or branched, substitutedor unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkylor cycloalkenyl; phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN,—COR₇, —CO₂R₇, —CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇,—(CH₂)_(n)OR₇, —(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is aninteger from 1 to 4; and wherein each of R₇ and R₈ is independently H;straight chain or branched, substituted or unsubstituted C₁-C₇ alkyl,C₂-C₇ alkenyl or alkynyl; phenyl or substituted phenyl.

[0011] These compounds are selective for cloned human alpha 2 receptorsand are useful as analgesic, sedative or anaesthetic agents.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention is directed to compounds having thestructure:

[0013] wherein each of R₁, R₂, R₃ and R₉ is independently H; straightchain or branched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl,substituted phenyl, or heteroaryl; wherein each dashed line represents asingle bond or a double bond with the proviso that if R₁ is present, R₃is absent and there is a double bond between N at position 3 and C atposition 2 and a single bond between C at position 2 and N at position 1and if R₃ is present, R₁ is absent and there is a double bond between Nat position 1 and C at position 2 and a single bond between C atposition 2 and N at position 3; wherein each of R₄, R₁ and R₆ isindependently H, F, Cl, Br, I; straight chain or branched, substitutedor unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkylor cycloalkenyl; phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN,—COR₇, —CO₂R₇, —CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇,—(CH₂)_(n)OR₇, —(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is aninteger from 1 to 4; and wherein each of R₇ and R₈ is independently H;straight chain or branched, substituted or unsubstituted C₁-C₇ alkyl,C₂-C₇ alkenyl or alkynyl; phenyl or substituted phenyl.

[0014] The compound may have the following preferred structure:

[0015] where each of R₁, R₂, R₃, R₄ and R₆ is defined above.

[0016] In addition, the invention further describes compounds having thefollowing structures:

[0017] Acid salts of the compounds described above may be also beprepared. The acid salts may be but are not limited to the followingHCl, HBr, HI, H₂SO₄, CH₃COOH, CF₃COOH, HNO₃, CF₃SO₃H, CH₃SO₃H, C₄H₄O₄,HO₂CCH═CHCO₂H, HO₂CCH═CHCO₂H, HO₂CCH(OH)CH(OH)CO₂H.

[0018] The invention also describes a pharmaceutical compositioncomprising a therapeutically effective amount of the compounds describedabove and a pharmaceutically acceptable carrier.

[0019] The invention further describes a method for treating an alpha-2adrenergic receptor associated disorder or alleviating pain in a subjectwhich comprises administering to the subject an amount of a compoundhaving the structure:

[0020] where each of R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈ and R₉ is definedabove.

[0021] The invention describes a method for treating an alpha-2adrenergic receptor associated disorder or alleviating pain in a subjectwhich comprises administering to the subject an amount of a compoundhaving the structure:

[0022] where each of R₁, R₂₁ R₃, R₄ and R₆ is defined above.

[0023] The invention describes a method for alleviating pain in asubject which comprises administering to the subject an amount of acompound having the structure:

[0024] The method described above may be used to treat alpha-2adrenergic receptor associated disorders such as hypertension,rheumatoid arthritis, ischemia, spasticity, glaucoma, migraines, alcoholwithdrawal, drug addiction, diarrhea, or nasal congestion.

[0025] The compounds may be administered to a subject suffering from analpha-2 adrenergic receptor associated disorder. The effective quantityof the compounds described above is from about 0.01 mg/dose to about 100mg/dose and preferably from about 0.1 mg/dose to about 20 mg/dose. Suchdose levels will depend upon the half-life of the compounds see forexample Goodman and Gilman's “The Pharmacological Basis ofTherapeutics,” Eighth Edition, 1990, Pergamon Press, pages 3-32.

[0026] Administration for the above compounds may be by any conventionalroute of administration, including, but not limited to, intravenous,intramuscular, oral, ophthalmic, subcutaneous, intratumoral,intradermal, and parenteral.

[0027] The present invention also provides compounds useful forpreparing a pharmaceutical composition comprising any of the compoundsdisclosed herein and a pharmaceutically acceptable carrier. Thecomposition may contain between 0.1 mg and 500 mg of any of thecompounds, and may be constituted in any form suitable for the mode ofadministration selected.

[0028] The compounds may be administered neat or with a pharmaceuticalcarrier to a patient in need thereof. The pharmaceutical carrier may besolid or liquid.

[0029] A solid carrier can include one or more substances which may alsoact as flavoring agents, lubricants, solubilizers, suspending agents,fillers, glidants, compression aids, binders or tablet-disintegratingagents; it can also be an encapsulating material. In powders, thecarrier is a finely divided solid which is in admixture with the finelydivided active ingredient. In tablets, the active ingredient is mixedwith a carrier having the necessary compression properties in suitableproportions and compacted in the shape and size desired. The powders andtablets preferably contain up to 99% of the active ingredient. Suitablesolid carriers include, for example, calcium phosphate, magnesiumstearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose,polyvinylpyrrolidine, low melting waxes and ion exchange resins.

[0030] Liquid carriers are used in preparing solutions, suspensions,emulsions, syrups, elixirs and pressurized compositions. The activeingredient can be dissolved or suspended in a pharmaceuticallyacceptable liquid carrier such as water, an organic solvent, a mixtureof both or pharmaceutically acceptable oils or fats. The liquid carriercan contain other suitable pharmaceutical additives such assolubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoringagents, suspending agents, thickening agents, colors, viscosityregulators, stabilizers or osmo-regulators. Suitable examples of liquidcarriers for oral and parenteral administration include water (partiallycontaining additives as above, e.g. cellulose derivatives, preferablysodium carboxymethyl cellulose solution), alcohols (including monohydricalcohols and polyhydric alcohols, e.g. glycols) and their derivatives,and oils (e.g. fractionated coconut oil and arachis oil). For parenteraladministration, the carrier can also be an oily ester such as ethyloleate and isopropyl myristate. Sterile liquid carriers are useful insterile liquid form compositions for parenteral administration. Theliquid carrier for pressurized compositions can be halogenatedhydrocarbon or other pharmaceutically acceptable propellent.

[0031] Liquid pharmaceutical compositions which are sterile solutions orsuspensions can be utilized by for example, intramuscular,intraperitoneal or subcutaneous injection. Sterile solutions can also beadministered intravenously. The compounds may be prepared as a sterilesolid composition which may be dissolved or suspended at the time ofadministration using sterile water, saline, or other appropriate sterileinjectable medium. Carriers are intended to include necessary and inertbinders, suspending agents, lubricants, flavorants, sweeteners,preservatives, dyes, and coatings.

[0032] The compound can be administered orally in the form of a sterilesolution or suspension containing other solutes or suspending agents,for example, enough saline or glucose to make the solution isotonic,bile salts, acacia, gelatin, sorbitan monoleate, polysorbate 80 (oleateesters of sorbitol and its anhydrides copolymerized with ethylene oxide)and the like.

[0033] The compound can also be administered orally either in liquid orsolid composition form. Compositions suitable for oral administrationinclude solid forms, such as pills, capsules, granules, tablets, andpowders, and liquid forms, such as solutions, syrups, elixirs, andsuspensions. Forms useful for parenteral administration include sterilesolutions, emulsions, and suspensions.

[0034] Optimal dosages to be administered may be determined by thoseskilled in the art, and will vary with the particular compound in use,the strength of the preparation, the mode of administration, and theadvancement of the disease condition. Additional factors depending onthe particular subject being treated will result in a need to adjustdosages, including subject age, weight, gender, diet, and time ofadministration.

[0035] This invention will be better understood from the ExperimentalDetails which follow. However, one skilled in the art will readilyappreciate that the specific methods and results discussed are merelyillustrative of the invention as described more fully in the claimswhich follow thereafter.

[0036] Experimental Details

[0037] General Methods

[0038] Four general synthetic methods were used to synthesize thecompounds described herein. These methods are illustrated in ReactionSchemes 1-4.

[0039] The compounds herein have been prepared using synthetic sequencesshown in Schemes 1-4. C-4 halogen substituted 5-aminobenzimidazoles wereobtained from commercially available 5-nitrobenzimidazole by thesequence of hydrogenation and halogenation. C-4 alkyl substitutedanalogs were prepared in a similar reaction sequence in which alkylgroup was incorporated using a Grignard reaction (Scheme 1). Reaction of5-aminobenzimidazole with 2-imidazoline-2-sulfonic acid (ISA) which wasobtained from 2-imidazolinethione (Gluchowski, C. U.S. Pat. No.5,130,441) provides access to 2-aminoimidazolines in high yield(45-95%). C-2 substituted 5-nitrobenzimidazoles were prepared bycondensation of 4-nitro-1,2-phenylenediamine with corresponding acids(Scheme 2). C-2 substituted 5-nitrobenzimidazoles were subjected to thesame reaction sequence as Scheme 1 to provide the desired final product.Reaction of alkyl halides with 5-nitrobenzimidazole in the presence ofNaH provided both N-1 and N-3 substituted benzimidazoles (Scheme 3). Thereaction mixtures were subjected to hydrogenation (H₂/Pd—C) to producethe corresponding amines, which were separated on column chromatography.Each amine was subjected to the reaction sequence described in Scheme 1to provide the final product.

[0040] Preparation of C-7 substituted benzimidazoles is illustrated inScheme 4. Halogenation of 2,4-dinitroaniline provided 6-halogensubstituted anilines, which were subjected to hydrogenation andcondensation in formic acid to provide 7-halosubstituted5-aminobenzimidazoles. These intermediates were coupled to ISA toprovide the desired products. C-7 alkyl substituted benzimidazoles wereprepared using a similar sequence of reactions. Accordingly,6-bromo-2,4-dinitroaniline was converted to 6-alkyl or aryl substitutedanalogs by the Pd(II) catalyzed coupling reaction. Conversion of alkylsubstituted anilines to benzimidazoles was carried out in same reactionsequences described in Scheme 2.

EXAMPLE 1

[0041] 5-(2-Imidazolin-2-ylamino)benzimidazole (#1)

[0042] 5-Aminobenzimidazole. A solution of 5-nitrobenzimidazole (4.0 g,25 mmol) and 10% Pd/C (0.5 g) was stirred under H₂ for 12 h. Thereaction mixture was filtered through Celite-assisted funnel andconcentrated in vacuo, yielding 3.2 g (25 mmol, >95%) of the desiredproduct, which was characterized by NMR and subjected to followingreactions without further purification.

[0043] 2-Imidazoline-2-sulfonic acid (ISA). ISA was prepared accordingto the procedure described in literature (Gluchowski, C. U.S. Pat. No.5,130,441, 1992). To a solution of 2-imidazolinethione (6.6 g, 65 mmol),sodium molybdate(IV) dihydrate (0.5 g, 2.1 mmol) and NaCl (1.5 g) in 150ml of distilled water was added 30% of H₂O₂ (50 ml, 450 mmol) for 1 h at−10° C. The reaction mixture was stored at −20° C. for 12 h and thenreaction temperature was slowly warmed up to 25° C. The white crystalobtained was filtered and dried in vacuo to provide 2.8 g (21 mmol, 32%)of the acid. The compound was used in the examples noted below.

[0044] 5-(2-Imidazolin-2-ylamino)benzimidazole. A solution of5-aminobenzimidazole (1.0 g, 7.5 mmol) and ISA (2.5 g, 18.8 mmol) in 10ml of isobutanol was stirred at reflux for 12 h. The reaction mixturewas concentrated in vacuo to yield an oily residue which was subjectedto silica gel column chromatography (20% NH₃ sat'd MeOH/EtOAc) toproduce 0.77 g (3.8 mmol, 53%) of the product. The product obtained wasconverted to the fumarate salt and recrystallized from MeOH to afford0.21 g (27%) of the product as a white solid: mp 196-198° C.; Anal.Calc. for C₁₀H₁₁N₅.1.0C₄H₄O₄₀.1.3H₂O requires C, 49.62; H, 4.65; N,20.67. Found: C, 49.65; H, 5.73; N, 20.53.

EXAMPLE 2

[0045] 4-Bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#2)

[0046] 4-Bromo-5-aminobenzimidazole. To a solution of5-aminobenzimidazole (0.3 g, 2.3 mmol) in 30 ml of AcOH was addedbromine (0.055 ml, 1.1 mmol) in a portion and resulting reaction mixturewas stirred for 0.5 h at 25° C. Reaction mixture was concentrated invacuo, yielding a dark brown solid which was subjected to silica gelcolumn chromatography (NH₃ saturated 10% MeOH/EtOAc) to yield 0.22 g(0.97 mmol, 42%) of the desired product.

[0047] 4-Bromo-5-(2-imidazolin-2-ylamino)benzimidazole. A solution of4-bromo-5-aminobenzimidazole (0.22 g, 0.97 mmol) and ISA (0.34 g, 2.5mmol) in 5 ml of isobutanol was stirred at reflux for 12 h. Reactionmixture was concentrated in vacuo and subjected to silica gel columnchromatography (NH₃ saturated 20% MeOH/EtOAc) to yield 0.23 g (0.83mmol, 84%) of the product. The product obtained was converted to thefumarate salt and recrystallized from MeOH to afford 0.12 g (30%) of theproduct as a white solid: mp 199-202° C.; Anal. Calc. forC₁₀H₁₀N₅Br.1.0C₄H₄O₄.0.7H₂O requires C, 41.13; H, 3.80; N, 17.13. Found:C, 41.60; H, 3.81; N, 16.97.

EXAMPLE 3

[0048] 4-Chloro-5-(2-imidazolin-2-ylamino)benzimidazole (#3)

[0049] 4-Chloro-5-aminobenzimidazole. To a solution of5-aminobenzimidazole (1.0 g, 7.5 mmol) in 20 ml of AcOH was added Cl₂saturated AcOH solution until it produced a precipitation. The reactionmixture was concentrated in vacuo, yielding a dark residue which wassubjected to column chromatography (NH₃ sat'd 30% MeOH/EtOAc) to yield120 mg (0.72 mmol) of 4-chloro-5-aminobenzimidazole.

[0050] 4-Chloro-5-(2-imidazolin-2-ylamino)benzimidazole. The amine (120mg, 0.72 mmol) was mixed with ISA (250 mg, 1.8 mmol), and resultingmixture was stirred for 12 h at reflux. Column chromatographicseparation (NH₃ sat'd 30% MeOH/EtOAc) of the reaction mixture yielded140 mg (0.62 mmol, 87%) of the desired product. The product obtained wasconverted to the fumarate salt and recrystallized from EtOH to afford 50mg (20%) of the product as a white solid: mp 207-208° C.; Anal. Calc.for C₁₀H₁₀N₅Cl.1.0C₄H₄O₄.0.6H₂O requires C, 46.38; H, 4.23; N, 19.32.Found: C, 46.32; H, 4.23; N, 19.47.

EXAMPLE 4

[0051] 4-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole (#4)

[0052] 4-Methyl-5-aminobenzimidazole. A solution of4-bromo-5-aminobenzimidazole (180 mg, 0.84 mmol), tetramethyltin (330mg, 2.4 mmol) and bis(triphenylphosphine)palladium (II) chloride (20 mg)in 5 ml of anhydrous DMF was placed in sealed tube and stirred for 12 hat 145° C. The reaction mixture was concentrated in vacuo, yielding anoily residue which was subjected to column chromatographic separation(NH₃ sat'd 10% MeOH/EtOAc) to yield 140 mg (0.83 mmol, >95%) of4-methyl-5-aminobenzimidazole.

[0053] 4-Methyl-5-(2-imidazolin-2-ylamino)benzimidazole. The amineobtained was placed in flask with ISA (0.38 g, 2.5 mmol) and 5 ml ofisobutanol, and resulting mixture was stirred at reflux for 12 h. Columnchromatographic separation (NH₃ sat'd 10% MeOH/EtOAc) of the reactionmixture provided 0.15 g (0.71 mmol, 84%) of the desired product. Theproduct obtained was converted to the fumarate salt and recrystallizedfrom MeOH to afford 92 mg (25%) of the product as a white solid: mp155-157° C.; Anal. Calc. for C₁₁H₁₃N₅.1.5C₄H₄O₄.0.5H₂O requires C,52.08; H, 4.96; N, 17.86. Found: C, 52.08; H, 4.97; N, 17.80.

EXAMPLE 5

[0054] 4-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole (#5)

[0055] 4-Iodo-5-aminobenzimidazole. To a solution of5-aminobenzimidazole (0.6 g, 4.5 mmol) and Hg(OAc)₂ (1.72 g, 5.5 mmol)in 20 ml of AcOH was added a solution of I₂ until solution produces aprecipitation. The reaction mixture was concentrated in vacuo, yieldingan oily residue which was subjected to column chromatographic separation(NH₃ sat'd 10% MeOH/EtOAc) to produce 0.30 (1.2 mmol, 26%) g of4-iodo-5-aminobenzimidazble.

[0056] 4-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole. A solution of theamine (0.30 g, 1.1 mmol) and ISA (0.62 g, 4.4 mmol) was stirred atreflux for 12 h. Column chromatographic separation of the reactionmixture (NH₃ sat'd 20% MeOH/EtOAc) provided 0.12 g (0.34 mmol, 31%) ofthe desired product. The product obtained was converted to the fumaratesalt and recrystallized from EtOH to afford 0.12 g (20%) of the productas a white solid: mp 256° C.; Anal. Calc. for C₁₀H₁₀N₅I.2.0C₄H₄O₄.1.0H₂Orequires C, 37.45; H, 3.49; N, 12.13. Found: C, 37.52; H, 3.51; N,12.62.

EXAMPLE 6

[0057] 4-Ethyl-5-(2-imidazolin-2-ylamino)benzimidazole (#6)

[0058] 4-Ethyl-5-aminobenzimidazole. To a solution of5-nitro-benzimidazole (2.8 g, 17 mmol) in THF was added 16 ml of EtMgBrsolution (48 mmol) and reaction mixture was stirred for 2 h at −15° C. Asolution of tetrachloro-1,4-benzoquinone (8.8 g, 36 mmol) in THF wasadded dropwise into reaction mixture, which was allowed to warm up to25° C. over 1 h. Silica gel(20 g) was added into reaction mixture andsolvent was removed in vacuo to provide a brown silica gel powder whichwas subjected to column chromatography (EtOAc, neat) to provide 1.7 g(8.9 mmol, 52%) of 4-ethyl-5-nitrobenzimidazole, which was subsequentlysubjected to hydrogenation (H₂, Pd/C) to yield 1.32 g (8.2 mmol) of4-ethyl-5-aminobenzimidazole.

[0059] 4-Ethyl-5-(2-imidazolin-2-ylamino)benzimidazole. A solution ofthe amine (0.71 g, 4.3 mmol) and ISA (0.75 g, 5.6 mmol) in 10 ml ofisobutanol was stirred at reflux for 12 h. The reaction mixture wasconcentrated in vacuo, yielding an oil, which was subjected to columnchromatography (NH₃ sat'd 30% EtOH/EtOAc) to yield 0.26 g (1.2 mmol,28%) of the desired product. The product obtained was converted to thefumarate salt and recrystallized from MeOH to afford 0.22 g (16%) of theproduct as a light brown solid: mp 238-239° C.; Anal. Calc. forC₁₂H₁₅N₅.1.0C₄H₄O₄ requires C, 55.60; H, 5.55; N, 20.28. Found: C,54.63; H, 5.70; N, 19.46.

EXAMPLE 7

[0060] 4-n-Propyl-5-(2-imidazolin-2-ylamino)benzimidazole (#7)

[0061] 4-n-Propyl-5-aminobenzimidazole. To a solution of5-nitrobenzimidazole (2.3 g, 14 mmol) was added 14 ml of n-PrMgBrsolution (42 mmol) and reaction mixture was stirred for 2 h at −15° C.The reaction was quenched by adding a solution oftetrachloro-1,4-benzoquinone (4 g, 16 mmol) in 10 ml of THF. Thereaction mixture was concentrated in vacuo to provide an oil, which wassubjected to column chromatographic separation (EtOAc, neat) to provide1.4 g (7.2 mmol, 52%) of 4-n-propyl-5-nitrobenzimidazole, which wasconverted to the corresponding amine (1.2 g, >95%) by hydrogenation(H₂,Pd/C).

[0062] 4-n-Propyl-5-(2-imidazolin-2-ylamino)benzimidazole. The amine(1.2 g, 14 mmol) was stirred with ISA (1.5 g, 11.2 mmol) at reflux for12 h. Concentration of reaction mixture produced an oily residue, whichwas subjected to column chromatographic separation (NH₃ sat'd 30%MeOH/EtOAc) to provide 0.63 g (2.6 mmol, 37%) of the desired product.The product obtained was converted to the fumarate salt andrecrystallized from EtOH to afford 0.45 g (16%) of the product as alight brown solid: mp 229-230° C.

EXAMPLE 8

[0063] 4-n-Butyl-5-(2-imidazolin-2-ylamino)benzimidazole (#8)

[0064] 4-n-Butyl-5-aminobenzimidazole. To a solution of5-nitrobenzimidazole (0.41 g, 2.5 mmol) was added a solution of n-BuLi(7.5 mmol) and reaction mixture was stirred for 1 h at 0° C. Thereaction mixture was quenched by adding a few drops of H₂O andconcentrated in vacuo yielding an oil which was subjected to silica gelcolumn chromatography (5% MeOH/EtOAC) to provide 0.13 g of4-n-butyl-5-nitrobenzimidazole and 0.19 g of4-n-butyl-5-aminobenzimidazole. The nitrobenzimidazole was converted tothe amine in hydrogenation (H₂/Pd-C) to provide 0.28 g (1.5 mmol, 60%)of the desired product.

[0065] 4-n-Butyl-5-(2-imidazolin-2-ylamino)benzimidazole. The amine(0.28 g, 1.5 mmol) was refluxed with ISA (0.50 g, 3.7 mmol) inisobutanol for 12 h. Column chromatographic separation of reactionmixture (NH₃ sat'd 20% MeOH/EtOAc) provided 0.21 g (0.81 mmol, 54%) ofthe product. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.38 g (49%) of the product asa foamy solid: mp 96° C.; Anal. Calc. for C₁₄H₁₉N₅.2.0C₄H₄O₄. requiresC, 55.68; H, 5.86; N, 16.23. Found: C, 55.98; H, 5.68; N, 16.49.

EXAMPLE 9

[0066] 1-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole (#9)

[0067] 1- and 3-Methyl-5-aminobenzimidazole. A solution of5-nitrobenzimidazole (3.0 g, 18.4 mmol) in 100 ml of THF was stirredwith NaH (2.7 g, 36.8 mmol) for 0.5 h at 25° C. To the solution wasadded methyl iodide (2.0 ml, 20.3 mmol) and resulting mixture wasstirred for 12 h. The reaction mixture was concentrated in vacuo toprovide an oil, which was dissolved in 200 ml of MeOH and stirred with0.3 g of 10% Pd/C under H₂ for 12 h. The reaction mixture was filteredand concentrated in vacuo, yielding a dark oily residue which wassubjected to column chromatography (3% MeOH/CHCl₃) to provide 0.69 g(3.9 mmol, 21%) of 1-methyl-5-aminobenzimidazole and 0.36 g (2.0 mmol,11%) of 3-methyl-5-aminobenzimidazole.

[0068] 1-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole A solution of1-methyl-5-aminobenzimidazole (0.15 g, 1.1 mmol) and ISA (0.30 g, 2.2mmol) in 3 ml of isobutanol was stirred at reflux for 12 h. The reactionmixture was concentrated in vacuo, yielding an oily residue which waspurified on silica gel column chromatography (NH₃ sat'd 20%isopropanol/EtOAc) to yield 0.12 g (0.56 mmol, 51%) of the desiredproduct. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.11 g (30%) of the product asa white crystal: mp 210-211° C.; Anal. Calc. forC₁₁H₁₃N₅.1.0C₄H₄O₄0.3H₂O requires C, 35.36; H, 5.28; N, 20.74. Found: C,53.67; H, 5.13; N, 20.70.

EXAMPLE 10

[0069] 1-Methyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#10)

[0070] 1-Methyl-4-bromo-5-aminobenzimidazole. To a solution of1-methyl-5-aminobenzimidazole (0.36 g, 2.4 mmol) in 10 ml of AcOH wasadded Br₂ (0.12 ml). The reaction mixture was stirred for 1 h at 25° C.and concentrated in vacuo, yielding an oil which was subjected to columnchromatography (NH₃ sat'd 3% MeOH/CHCl₃) to yield 0.27 g (1.2 mmol, 50%)of the desired product.

[0071] 1-Methyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole.Isobutanolic solution of the amine (0.27 g, 1.2 mmol) and ISA (0.6 g,4.5 mmol) was stirred at reflux for 12 h. The reaction mixture wasconcentrated in vacuo, yielding an oily residue which was subjected tocolumn chromatography (NH₃ sat'd 20% MeOH/EtOAc) to yield 0.33 g (1.1mmol, 92%) of the expected product. The product obtained wasrecrystallized from EtOH to afford 0.21 g (64%) of the product as awhite crystal: mp 237-238° C.; Anal. Calc. for C₁₁H₁₂N₅Br.1.75H₂Orequires C, 40.57; H, 4.80; N, 21.50. Found: C, 40.98; H, 4.81; N,21.41.

EXAMPLE 11

[0072] 3-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole. (#11) Asolution of 3-methyl-5-aminobenzimidazole (0.20 g, 1.5 mmol) and ISA(0.45 g, 3.4 mmol) was stirred at reflux for 12 h. The reaction mixturewas concentrated in vacuo and purified on column chromatography (NH₃sat'd 20% MeOH/EtOAc) to yield 0.19 g (0.88 mmol, 59%) of the product.The product obtained was converted to the fumarate salt andrecrystallized from MeOH to afford 0.31 g (46%) of the product as awhite crystal: mp 202-204° C.; Anal. Calc. for C₁₁H₁₃N₅.2.0C₄H₄O₄requires C, 51.01; H, 4.73; N, 15.65. Found: C, 51.65; H, 4.76; N,15.78.

EXAMPLE 12

[0073] 3-Methyl-4-bromo-5-(imidazolin-2-ylamino)benzimidazole (#12)

[0074] 3-Methyl-4-bromo-5-aminobenzimidazole. To a solution of3-methyl-5-aminobenzimidazole (0.27 g, 1.8 mmol) in 10 ml of AcOH wasadded Br₂ (0.10 ml). The reaction mixture was stirred for 1 h at 25° C.and concentrated in vacuo, yielding an oil which was subjected to columnchromatography (NH₃ sat'd 3% MeOH/CHCl₃) to yield 0.14 g (0.62 mmol,35%) of the desired product.

[0075] 3-Methyl-4-bromo-5-(imidazolin-2-ylamino)benzimidazole. Asolution of 3-methyl-4-bromo-5-aminobenzimidazole (0.31 g, 1.4 mmol) andISA (0.6 g, 4.5 mmol) in 10 ml of isobutanol was stirred at reflux for12 h. Oily residue obtained was subjected to column chromatography (NH₃sat'd 20% isopropanol/EtOAc) to yield 0.39 g (1.3 mmol, 93%) of thedesired product. The product obtained was converted to the fumarate saltand recrystallized from MeOH to afford 0.50 g (68%) of the product as awhite solid: mp 209-210° C.; Anal. Calc. for C₁₁H₁₂N₅Br.2.0C₄H₄O₄.requires C, 43.36; H, 3.83; N, 13.31. Found: C, 43.66; H, 3.84; N,13.10.

EXAMPLE 13

[0076] 1-Propyl-5-(2-imidazolin-2-ylamino)benzimidazole (#13)

[0077] 1- and 3-Propyl-5-aminobenzimidazole. A solution of5-nitrobenzimidazole (3.6 g, 23 mmol) in 100 ml of THF was stirred withNaH (1.5 g, 33 mmol) for 0.5 h at 25° C. To the solution was added allylbromide (4.8 ml, 57 mmol) and resulting mixture was stirred for 12 h.The reaction mixture was concentrated in vacuo to provide an oil, whichwas subjected to column chromatography to yield 4.0 g (19.7 mmol, 89%)of a mixture of 1- and 3-allyl-5-nitrobenzimidazole. Thenitrobenzimidazole mixture was stirred in 100 ml of MeOH for 12 under H₂in the presence of 10% Pd/C. The reaction mixture was filtered andconcentrated in vacuo to provide oily residue which was subjected tocolumn chromatography (50% Hexane/EtOAc) to provide 1.2 g (7.0 mmol) of1-propyl-5-aminobenzimidazole and 1.1 g (6.4 mmol) of3-propyl-5-aminobenzimidazole.

[0078] 1-Propyl-5-(2-imidazolin-2-ylamino)benzimidazole. Reaction of1-propyl-5-aminobenzimidazole (1.2 g, 7.0 mmol) and ISA (2.2 g, 16 mmol)provided 1.6 g (6.6 mmol, 94%) of the expected product after columnchromatographic separation. The product obtained was converted to thefumarate salt and recrystallized from MeOH to afford 2.1 g (76%) of theproduct as a light brown solid: mp 206-207° C.; Anal. Calc. forC₁₃H₁₇N₅.1.5C₄H₄O₄ requires C, 54.67; H, 5.55; N, 16.98. Found: C,54.60; H, 5.49; N, 17.16.

EXAMPLE 14

[0079] 1-Propyl-4-bromo-5-(imidazolin-2-ylamino)benzimidazole (#14)

[0080] 1-Propyl-4-bromo-5-aminobenzimidazole. To a solution of1-propyl-5-aminobenzimidazole (1.2 g, 7.1 mmol) in 10 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 0.83 g (3.4 mmol, 48%) of the product.

[0081] 1-Propyl-4-bromo-5-(imidazolin-2-ylamino)benzimidazole. Areaction of the amine (0.83 g, 3.4 mmol) and ISA (1.3 g, 9.7 mmol)produced 0.44 g (1.3 mmol, 38%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.32 g (25%) of the product asa light brown solid: mp 206-207° C.; Anal. Calc. forC₁₃H₁₆N₅Br.0.5C₄H₄O₄.0.5H₂O requires C, 46.29; H, 4.92; N, 17.99. Found:C, 46.66; H, 4.86; N, 17.60.

EXAMPLE 15

[0082] 3-Propyl-5-(2-imidazolin-2-ylamino)benzimidazole. (#15) Areaction of 3-propyl-5-aminobenzimidazole (1.0 g, 5.8 mmol) and ISA (1.9g, 14 mmol) provided 1.3 g (5.0 mmol, 87%) of product after columnchromatography. The product obtained was converted to the fumarate saltand recrystallized from isopropanol to afford 0.32 g (25%) of theproduct as a white solid: mp 198-199° C.; Anal. Calc. forC₁₃H₁₇N₅1.0C₄H₄O₄ requires C, 56.82; H, 5.89; N, 19.49. Found: C, 57.12;H, 5.91; N, 19.61.

EXAMPLE 16

[0083] 3-Propyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#16)

[0084] 3-Propyl-4-bromo-5-aminobenzimidazole. To a solution of3-propyl-5-aminobenzimidazole (0.71 g, 4.3 mmol) in 10 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 0.40 g (1.6 mmol, 37%) of the product.

[0085] 3-Propyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-propyl-4-bromo-5-aminobenzimidazole (0.40 g, 1.6 mmol) andISA (0.7 g, 5.2 mmol) provided 0.32 g (1.3 mmol, 81%) of product aftercolumn chromatography. The product obtained was converted to thefumarate salt and recrystallized from isopropanol to afford 0.30 g (58%)of the product as a white solid: mp 179-181° C.; Anal. Calc. forC₁₃H₁₆N₅Br1.0C₄H₄O₄ requires C, 46.59; H, 4.60; N, 15.98. Found: C,46.36; H, 4.49; N, 15.81.

EXAMPLE 17

[0086] 1-Isopropyl-S-(2-imidazolin-2-ylamino)benzimidazole (#17)

[0087] 1- and 3-Isopropyl-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (4.8 g, 29 mmol) and isopropyl bromide (˜3.7 ml) ina procedure described in Example 9 produces 5.1 g (23 mmol, 81%) of amixture of 1- and 3-isopropyl-5-nitrobenzimidazole, which was convertedto the corresponding amines in hydrogenation (H₂/Pd-C). The aminemixture was subjected to column chromatography (10% i-PrOH/CH₂Cl₂) toprovide 1.5 g (7.9 mmol, 27%) of 1-isopropyl-5-aminobenzimidazole and2.4 g (12.6 mmol, 44%) of 3-isopropyl-5-aminobenzimidazole.

[0088] 1-Isopropyl-5-(2-imidazolin-2-ylamino)benzimidazole. Reaction of1-isopropyl-5-aminobenzimidazole (0.41 g, 2.3 mmol) and ISA (0.70 g, 5.2mmol) provided 0.37 g (1.5 mmol, 66%) of the expected product aftercolumn chromatographic separation. The product obtained was converted tothe fumarate salt and recrystallized from isopropanol to afford 0.27 g(24%) of the product as a light brown solid: mp 185-186° C.; Anal. Calc.for C₁₃H₁₇N₅.2.0C₄H₄O₄ requires C, 52.83; H, 5.70; N, 14.67. Found: C,53.32; H, 5.63; N, 14.97.

EXAMPLE 18

[0089] 1-Isopropyl-4-bromo-S-(2-imidazolin-2-ylamino) benzimidazole(#18)

[0090] 1-Isopropyl-4-bromo-5-aminobenzimidazole. To a solution of1-isopropyl-5-aminobenzimidazole (2.4 g, 14 mmol) in 20 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 1.2 g (4.5 mmol, 35%) of the product.

[0091] 1-Isopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the amine (0.86 g, 3.4 mmol) and ISA (0.90 g, 6.7 mmol)produced 0.67 g (2.1 mmol, 61%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.55 g (37%) of the product asa light brown solid: mp 187-188° C.; Anal. Calc. forC₁₃H₁₆N₅Br.1.0OC₄H₄O₄ requires C, 46.59; H, 4.60; N, 15.98. Found: C,46.35; H, 4.49; N, 15.82.

EXAMPLE 19

[0092] 1-Isopropyl-4-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole (#19)

[0093] 1-Isopropyl-4-iodo-5-aminobenzimidazole. To a solution of1-isopropyl-5-aminobenzimidazole (0.70 g, 3.7 mmol) and Hg(OAc)₂ (2.1 g,5.6 mmol) in 10 ml of AcOH was added solution of 12 in AcOH until itproduces a precipitation: The reaction mixture was concentrated in vacuoto provide a brown solid which was subjected to column chromatography(5% NH₃ sat'd MeOH/CH₂Cl₂) to provide 0.40 g (1.3 mmol, 35%) of theproduct. 1-Isopropyl-4-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the amine (0.40 g, 1.3 mmol) and ISA (0.5 g, 3.7 mmol)produced 0.18 g (0.48 mmol, 37%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.22 g (35%) of the product asa white solid: mp 208-209° C.; Anal. Calc. for C₁₃H₁₆N₅I.1.0C₄H₄O₄requires C, 42.08; H, 4.15; N, 14.43. Found: C, 41.86; H, 4.08; N,14.17.

EXAMPLE 20

[0094] 3-Isopropyl-5-(2-imidazolin-2-ylamino)benzimidazole. (#20). Areaction of 3-isopropyl-5-aminobenzimidazole (1.0 g, 5.8 mmol) and ISA(1.5 g, 11 mmol) yielded 0.90 g (3.8 mmol, 65%) of product after columnchromatography. The product obtained was converted to the fumarate saltand recrystallized from isopropanol to afford 0.32 g (25%) of theproduct as a light brown solid: mp 206-207° C.; Anal. Calc. forC₁₃H₁₇N₅0.5C₄H₄O₄ requires C, 54.67; H, 5.55; N, 16.78. Found: C, 53.33;H, 5.50; N, 16.30.

EXAMPLE 21

[0095] 3-Isopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#21)

[0096] 3-Isopropyl-4-bromo-5-aminobenzimidazole. To a solution of3-isopropyl-5-aminobenzimidazole (1.5 g, 7.9 mmol) in 20 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 1.1 g (4.0 mmol, 47%) of the product.

[0097] 3-Isopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-isopropyl-4-bromo-5-aminobenzimidazole (1.1 g, 4.0 mmol)and ISA (1.2 g, 9.0 mmol) provided 0.6 g (1.9 mmol, 43%) of productafter column chromatography. The product obtained was converted to thefumarate salt and recrystallized from EtOH to afford 0.52 g (28%) of theproduct as a white crystal: mp 210-212° C.; Anal. Calc. forC₁₃H₁₆N₅Br.1.0C₄H₄O₄ requires C, 46.59; H, 4.60; N, 15.98. Found: C,46.60; H, 4.49; N, 15.74.

EXAMPLE 22

[0098] 1-Isobutyl-5-(2-imidazolin-2-ylamino)benzimidazole (#22)

[0099] 1- and 3-Isobutyl-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (4.8 g, 29 mmol) and isobutyl bromide (7.7 ml, 72mmol) in a procedure described in Example 9 produces 5.3 g (24 mmol,83%) of a mixture of 1- and 3-isopropyl-5-nitrobenzimidazole, which wasconverted to the corresponding amines in hydrogenation (H₂/Pd-C). Theamine mixture was subjected to column chromatography (10% i-PrOH/CH₂Cl₂)to provide 1.8 g (9.4 mmol, 32%) of 1-isobutyl-5-aminobenzimidazole and2.7 g (14 mmol, 49%) of 3-isobutyl-5-aminobenzimidazole.

[0100] 1-Isobutyl-5-(2-imidazolin-2-ylamino)benzimidazole. Reaction of1-isobutyl-5-aminobenzimidazole (0.29 g, 1.2 mmol) and ISA (0.6 g, 4.5mmol) provided 0.37 g (1.2 mmol, >95%) of the expected product aftercolumn chromatographic separation. The product obtained was converted tothe fumarate salt and recrystallized from isopropanol to afford 0.41 g(70%) of the product as a white solid: mp 185-186° C.; Anal. Calc. forC₁₄H₁₉N₅.2.0C₄H₄O₄ requires C, 53.98; H, 5.56; N, 14.31. Found: C,53.85; H, 5.69; N, 14.22.

EXAMPLE 23

[0101] 1-Isobutyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#23)

[0102] 1-Isobutyl-4-bromo-5-aminobenzimidazole. To a solution of1-isobutyl-5-aminobenzimidazole (2.4 g, 13 mmol) in 20 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 1.2 g (4.5 mmol, 35%) of the product.

[0103] 1-Isobutyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of bromoamine (0.30 g, 1.1 mmol) and ISA (0.9 g, 6.7 mmol)produced 0.28 g (0.81 mmol, 73%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.28 g (56%) of the product asa white solid: mp 226-227° C.

EXAMPLE 24

[0104] 3-Isobutyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#24)

[0105] 3-Isobutyl-4-bromo-5-aminobenzimidazole. To a solution of3-isobutyl-5-aminobenzimidazole (1.5 g, 7.9 mmol) in 20 ml of AcOH wasadded solution of. Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 1.0 g (3.7 mmol, 29%) of the product.

[0106] 3-Isobutyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-isobutyl-4-bromo-5-aminobenzimidazole (0.30 g, 1.1 mmol)and ISA (0.70 g, 5.2 mmol) provided 0.20 g (0.56 mmol, 51%) of theproduct after column chromatography. The product obtained was convertedto the fumarate salt and recrystallized from isopropanol to afford 0.22g (45%) of the product as a white solid: mp 187-188° C.; Anal. Calc. forC₁₄H₁₈N₅Br.1.0C₄H₁₄requires C, 47.80; H, 4.90; N, 15.48. Found: C,47.57; H, 4.61; N, 15.38.

EXAMPLE 25

[0107] 1-Cyclopentyl-5-(2-imidazolin-2-ylamino)benzimidazole (#25)

[0108] 1- and 3-Cyclopentyl-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (3.1 g, 19 mmol) and cyclopentyl bromide (3.8 ml,38 mmol) in a procedure described in Example 9 produces 2.6 g (11 mmol,59%) of a mixture of 1- and 3-cyclopentyl-5-nitrobenzimidazole, whichwas converted to the corresponding amines in hydrogenation (H₂/Pd—C).The amine mixture was subjected to column chromatography (10%i-PrOH/CH₂Cl₂) to provide 1.0 g (5.0 mmol, 45%) of1-cyclopentyl-5-aminobenzimidazole and 1.1 g (5.4 mmol, 50%) of3-cyclopentyl-5-aminobenzimidazole.

[0109] 1-Cyclopentyl-S-(2-imidazolin-2-ylamino)benzimidazole. A reactionof 1-cyclopentyl-5-aminobenzimidazole (0.66 g, 3.3 mmol) and ISA (1.3 g,9.7 mmol) provided 0.91 g (2.7 mmol, 81%) of the expected product aftercolumn chromatographic separation. The product obtained was converted tothe fumarate salt and recrystallized from isopropanol to afford 1.1 g(77%) of the product as a white crystal: mp 214-215° C.; Anal. Calc. forC₁₅H₁₉N₅.1.5C₄H₄,₄ requires C, 56.88; H, 5.68; N, 15.79. Found: C,56.69; H, 5.54; N, 16.02.

EXAMPLE 26

[0110] 1-Cyclopentyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#26)

[0111] 1-Cyclopentyl-4-bromo-5-aminobenzimidazole. To a solution of1-cyclopentyl-5-aminobenzimidazole (1.1 g, 5.5 mmol) in 20 ml of AcOHwas added solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 0.54 g (1.9 mmol, 35%) of the product.

[0112] 1-Cyclopentyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the amine (0.54 g, 1.9 mmol) and ISA (0.74 g, 5.5 mmol)produced 0.45 g (1.3 mmol, 67%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.32 g (19%) of the product asa light brown solid: mp 180-182° C.; Anal. Calc. forC₁₅H₁₈N₅Br.1.5C₄H₄O₄ requires C, 48.29; H, 4.63; N, 13.41. Found: C,48.56; H, 4.54; N, 13.23.

EXAMPLE 27

[0113] 3-Cyclopentyl-5-(2-imidazolin-2-ylamino)benzimidazole (#27). Areaction of 3-cyclopentyl-5-aminobenzimidazole (0.41 g, 2.0 mmol) andISA (0.68 g, 5.1 mmol) yielded 0.34 g (1.2 mmol, 62%) of product aftercolumn chromatography. The product obtained was converted to thefumarate salt and recrystallized from isopropanol to afford 0.28 g (31%)of the product as a white solid: mp 158-159° C.; Anal. Calc. forC₁₅H₁₉N₅.1.0C₄H₄O₄ requires C, 56.88; H, 5.68; N, 15.79. Found: C,55.69; H, 5.62; N, 15.73.

EXAMPLE 28

[0114] 3-Cyclopentyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#28)

[0115] 3-Cyclopentyl-4-bromo-5-aminobenzimidazole. To a solution of3-cyclopentyl-5-aminobenzimidazole (1.0 g, 5.0 mmol) in 20 ml of AcOHwas added solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CH₂Cl₂)to provide 0.70 g (2.5 mmol, 50%) of the product.

[0116] 3-Cyclopentyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-cyclopentyl-4-bromo-5-aminobenzimidazole (0.70 g, 2.5mmol) and ISA (0.94 g, 7.0 mmol) provided 0.26 g (0.78 mmol, 31%) ofproduct after column chromatography. The product obtained was convertedto the fumarate salt and recrystallized from isopropanol to afford 0.31g (27%) of the product as a white solid: mp 208-210° C.; Anal. Calc. forC₁₅H₁₉N₅Br.1.0C₄H₄,₄ requires C, 49.15; H, 4.78; N, 15.08. Found: C,49.46; H, 4.88; N, 15.38.

EXAMPLE 29

[0117] 1-Cyclohexylmethyl-5-(2-imidazolin-2-ylamino)benzimidazole (#29)

[0118] 1- and 3-Cyclohexylmethyl-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (3.1 g, 19 mmol) and cyclohexylmethyl bromide (6.7ml, 47 mmol) in a procedure described in Example 9 produces 5.0 g (19mmol, 100%) of a mixture of 1- and3-cyclohexylmethyl-5-nitrobenzimidazole, which was converted to thecorresponding amines in hydrogenation (H₂/Pd-C) The amine mixture was,subjected to column chromatography (10%-30% hexane/EtOAc) to provide 2.0g (8.7 mmol, 45%) of 1-cyclohexylmethyl-5-aminobenzimidazole and 2.5 g(11 mmol, 54%) of 3-cyclohexylmethyl-5-aminobenzimidazole.

[0119] 1-Cyclohexylmethyl-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 1-cyclohexylmethyl-5-aminobenzimidazole (2.2 g, 9.6 mmol)and ISA (3.6 g) provided 1.8 g (8.1 mmol, 84%) of the expected productafter column chromatographic separation. The product obtained wasconverted to the fumarate salt and recrystallized from isopropanol toafford 1.9 g (4.6 mmol, 48%) of the product as a white solid: mp222-223° C.; Anal. Calc. for C₁₇H₂₃N₅.1.0C₄H₄O₄ requires C, 61.00; H,6.58; N, 16.94. Found: C, 61.48; H, 6.41; N, 16.36.

EXAMPLE 30

[0120]1-Cyclohexylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#30)

[0121] 1-Cyclohexylmethyl-4-bromo-5-aminobenzimidazole. To a solution of1-cyclohexylmethyl-5-aminobenzimidazole (2.5 g, 11 mmol) in 20 ml ofAcOH was added solution of Br₂ in AcOH until it produces aprecipitation. The reaction mixture was concentrated in vacuo to providea brown solid which was subjected to column chromatography (5% NH₃ sat'dMeOH/CH₂Cl₂) to provide 1.37 g (4.3 mmol, 40%) of the product.

[0122]1-Cyclohexylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the amine (1.4 g, 4.4 mmol) and ISA (1.8 g, 13 mmol)produced 1.6 g (4.1 mmol, 94%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 1.8 g (83%) of the product asa white solid: mp 193-195° C.; Anal. Calc. for C₁₇H₂₂N₅Br.1.0C₄H₄O₄requires C, 51.23; H, 5.32; N, 14.22. Found: C, 50.21; H, 5.17; N,14.29.

EXAMPLE 31

[0123]3-Cyclohexylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#31)

[0124] 3-Cyclohexylmethyl-4-bromo-5-aminobenzimidazole. To a solution of3-cyclohexylmethyl-5-aminobenzimidazole (2.0 g, 8.7 mmol) in 40 ml ofAcOH was added solution of Br₂ in AcOH until it produces aprecipitation. The reaction mixture was concentrated in vacuo to providea brown solid which was subjected to column chromatography (5% NH₃ sat'dMeOH/CHCl₃) to provide 1.2 g (3.8 mmol, 48%) of the product.

[0125]3-Cyclohexylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-cyclohexylmethyl-4-bromo-5-aminobenzimidazole (1.2 g, 3.9mmol) and ISA (1.5 g, 11 mmol) provided 0.85 g (2.3 mmol, 58%) ofproduct after column chromatography. The product obtained was convertedto the fumarate salt and recrystallized from isopropanol to afford 1.1 g(51%) of the product as a white solid: mp 153-155° C.; Anal. Calc. forC₁₇H₂₂N₅Br.1.5C₄H₄O₄.0.5H₂O requires C, 49.38; H, 5.22; N, 12.58. Found:C, 49.22; H, 5.07; N, 12.19.

EXAMPLE 32

[0126] 1-Benzyl-5-(2-imidazolin-2-ylamino)benzimidazole (#32)

[0127] 1- and 3-Benzyl-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (3.0 g, 18 mmol) and benzyl bromide (4.4 ml, 37mmol) in a procedure described in Example 9 produces 3.2 g (13 mmol,71%) of a mixture of 1- and 3-benzyl-5-nitrobenzimidazole, which wasconverted to the corresponding amines in hydrogenation (H₂/Pd—C). Theamine mixture was subjected to column chromatography (10%-30%Hexane/EtOAc) to provide 1.6 g (7.2 mmol, 55%) of1-benzyl-5-aminobenzimidazole and 1.2 g (5.3 mmol, 41%) of3-benzyl-5-aminobenzimidazole.

[0128] 1-Benzyl-5-(2-imidazolin-2-ylamino)benzimidazole. A reaction of1-benzyl-5-aminobenzimidazole (0.35 g, 1.2 mmol) and ISA (0.42 g, 3.1mmol) provided 0.17 g (0.46 mmol, 38%) of the expected product aftercolumn chromatographic separation. The product obtained was converted tothe fumarate salt and recrystallized from isopropanol to afford 0.11 g(20%) of the product as a white solid: mp 174-175° C.; Anal. Calc. forC₁₇H₁₇N₅.1.5C₄H₄O₄ requires C, 59.35; H, 4.98; N, 45.05. Found: C,59.40; H, 4.81; N, 14.99.

EXAMPLE 33

[0129] 1-Benzyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#33)

[0130] 1-Benzyl-4-bromo-5-aminobenzimidazole. To a solution of1-benzyl-5-aminobenzimidazole (1.0 g, 5.0 mmol) in 40 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitate. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CHCl₃)to provide 0.90 g (2.5 mmol, 60%) of the product.

[0131] 1-Benzyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of bromoamine (0.90 g, 3.0 mmol) and ISA (1.2 g, 8.9 mmol)produced 0.85 g (2.3 mmol, 77%) of the product after chromatographicseparation. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 1.1 g (70%) of the product asa white solid: mp 197-198° C.; Anal. Calc. for C₁₇H₁₆N₅Br.1.5C₄H₄O₄requires C, 50.75; H, 4.07; N, 12.87. Found: C, 50.91; H, 3.87; N,12.77.

EXAMPLE 34

[0132] 3-Benzyl-5-(2-imidazolin-2-ylamino)benzimidazole (#34). Areaction of 3-benzyl-5-aminobenzimidazole (0.34 g, 1.6 mmol) and ISA(0.68 g, 5.1 mmol) yielded 0.43 g (1.3 mmol, 76%) of product aftercolumn chromatography. The product obtained was converted to thefumarate salt and recrystallized from isopropanol to afford 0.32 g (41%)of the product as a white solid: mp 174-175° C.; Anal. Calc. forC₁₇H₁₇N₅.1.5C₄H₄O₄ requires C, 59.35; H, 4.98; N, 15.05. Found: C,58.88; H, 5.19; N, 15.25.

EXAMPLE 35

[0133] 3-Benzyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#35)

[0134] 3-Benzyl-4-bromo-5-aminobenzimidazole. To a solution of3-benzyl-5-aminobenzimidazole (0.88 g, 3.9 mmol) in 20 ml of AcOH wasadded solution of Br₂ in AcOH until it produces a precipitation. Thereaction mixture was concentrated in vacuo to provide a brown solidwhich was subjected to column chromatography (5% NH₃ sat'd MeOH/CHCl₃)to provide 0.35 g (1.2 mmol, 29%) of the product.

[0135] 3-Benzyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 3-benzyl-4-bromo-5-aminobenzimidazole(0.35 g, 1.2 mmol) andISA (0.43 g, 3.2 mmol) provided 0.17 g (0.46 mmol, 38%) of the productafter column chromatography. The product obtained was converted to thefumarate salt and recrystallized from MeOH to afford 0.12 g (21%) of theproduct as a white solid: mp 203-205° C.; Anal. Calc. forC₁₇H₁₆N₅Br.1.0C₄H₄,₄ requires C, 51.87; H, 4.64; N, 14.39. Found: C,52.60; H, 4.73; N, 14.39.

EXAMPLE 36

[0136] 1-(4-Methoxybenzyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#36)

[0137] 1-(4-Methoxybenzyl)-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (4.3 g, 27 mmol) and 4-methoxybenzyl chloride (4.3ml, 30 mmol) in a procedure described in Example 9 produces 5.6 g (19mmol, 73%) of a mixture of 1- and3-(4-methoxybenzyl)-5-nitrobenzimidazole, which was converted to thecorresponding amines in hydrogenation (H₂/Pd—C). The amine mixture wassubjected to column chromatography (10%-30% i-PrOH/CH₂Cl₂) to provide2.1 g (8.2 mmol, 43%) of 1-(4-methoxybenzyl)-5-aminobenzimidazole and2.4 g (9.2 mmol, 48%) of 3-(4-methoxybenzyl)-5-aminobenzimidazole.

[0138] 1-(4-Methoxybenzyl)-4-bromo-5-aminobenzimidazole. To a solutionof 1-(4-methoxybenzyl)-5-aminobenzimidazole (0.80 g, 2.2 mmol) in 20 mlof AcOH was added solution of Br₂ in AcOH until it produces aprecipitation. The reaction mixture was concentrated in vacuo to providea brown solid which was subjected to column chromatography (5% NH₃ sat'dMeOH/CHCl₃) to provide 0.90 g (2.1 mmol, 95%) of the product.

[0139]1-(4-Methoxybenzyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the bromoamine (0.90 g, 2.1 mmol) and ISA (1.3 g, 9.7 mmol)provided 1.0 g (2.0 mmol, 96%) of the product after columnchromatography.

EXAMPLE 37

[0140]1-(3-Methoxybenzyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#37)

[0141] 1-(3-Methoxybenzyl)-5-aminobenzimidazole. A reaction of5-nitrobenzimidazole (2.5 g, 15 mmol) and 3-methoxybenzyl chloride (2.6ml, 17 mmol) in a procedure described in Example 9 produces 1.0 g (3.1mmol, 26%) of a mixture of 1- and3-(3-methoxybenzyl)-5-nitrobenzimidazole, which was converted to thecorresponding amines in hydrogenation (H₂/Pd—C). The amine mixture wassubjected to column chromatography (10%-30% isopropanol/CH₂Cl₂) toprovide 0.32 g (1.1 mmol, 36%) of3-(3-methoxybenzyl)-5-aminobenzimidazole and 0.37 g (1.3 mmol, 41%) of1-(3-methoxybenzyl)-5-aminobenzimidazole.

[0142] 1-(3-Methoxybenzyl)-4-bromo-5-aminobenzimidazole. To a solutionof 1-(3-methoxybenzyl)-5-aminobenzimidazole (0.37 g, 1.3 mmol) in 10 mlof AcOH was added solution of Br₂ in AcOH until it produces aprecipitation. The reaction mixture was concentrated in vacuo to providea brown solid which was subjected to column chromatography (5% NH₃ sat'dIsopropanol/CHCl₃) to provide 0.31 g (1.0 mmol, 66%) of the product.

[0143]1-(3-Methoxybenzyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the bromoamine (0.31 g, 0.84 mmol) and ISA (0.52 g, 3.9mmol) provided 0.37 g (>95%) of product after column chromatography. Theproduct obtained was converted to the fumarate salt and recrystallizedfrom isopropanol to afford 0.36 g (83%) of the product as a whitecrystal: mp 177-178° C.; Anal. Calc. for C₁₈H₁₈N₅BrO.1.0C₄H₄O₄.H₂Orequires C, 48.63; H, 4.64; N, 12.89. Found: C, 48.06; H, 4.51; N,12.77.

EXAMPLE 38

[0144]1-(2-Hydroxyethyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#38)

[0145] 1- and 3-(2-Hydroxyethyl)-4-bromo-5-aminobenzimidazole. Areaction of 5-nitrobenzimidazole (3.3 g, 20 mmol) and 2-hydroxyethylbromide (2.2 ml, 31 mmol) in a procedure described in Example 9 producesa mixture of 1- and 3-(2-hydroxyethyl)-5-nitrobenzimidazole, which wasconverted to the corresponding amines in hydrogenation (H₂/Pd—C). Theamine mixture (3.4 g, 19 mmol) in 50 ml of AcOH was added solution ofBr₂ in AcOH until it produces a precipitation. The reaction mixture wasconcentrated in vacuo to provide a brown solid which was subjected tocolumn chromatography (5% NH₃ sat'd isopropanol/CHCl₃) to provide 0.42 g(1.6 mmol) of 3-(2-hydroxyethyl)-4-bromo-5-aminobenzimidazole and 0.57 g(2.2 mmol, 11%) of 1-(2-hydroxyethyl)-4-bromo-5-aminobenzimidazole.

[0146]1-(2-Hydroxyethyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 1-(2-hydroxyethyl)-4-bromo-5-aminobenzimidazole (0.25 g, 1.4mmol) and ISA (0.35 g, 2.6 mmol) provided 0.21 g (0.87 mmol, 62%) ofproduct after column chromatography. The product obtained was convertedto the fumarate salt and recrystallized from isopropanol to afford 0.17g (28%) of the product as a white solid: mp 141-143° C.; Anal. Calc. forC₁₂H₁₄N₅OBr.1.0C₄H₄O₄ requires C, 43.55; H, 4.12; N, 15.87. Found: C,44.14; H, 4.03; N, 15.53.

EXAMPLE 39

[0147]3-(2-Hydroxyethyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#39). A reaction of 3-(2-hydroxy-1-ethyl)-4-bromo-5-aminobenzimidazole(0.31 g, 1.8 mmol) and ISA-(0.52 g, 3.9 mmol) provided 0.37 g (1.6 mmol,88%) of the desired product after column chromatography. The productobtained was converted to the fumarate salt and recrystallized fromisopropanol to afford 0.32 g (40%) of the product as a white solid: mp217-218° C.

EXAMPLE 40

[0148] 1-(2-Aminoethyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#40). To a solution of 1-(2-hydroxyethyl)-5-nitrobenzimidazole (0.27 g,1.3 mmol) was added triphenylphosphine (0.38 g, 1.4 mmol), DEAD (0.25ml, 1.4 mmol) and phthalimide (0.21 g, 1.4 mmol) in a portion andresulting mixture was stirred for 1 h at 25° C. The reaction mixture wasconcentrated in vacuo, yielding an oil which was subjected to columnchromatography (40% Hexane/EtOAc) to provide 0.36 g (1.1 mmol, 82%) of1-(2-phthalimidylethyl)-5-nitrobenzimidazole. The nitrobenzimidazole wassubsequently subjected to hydrogenation, bromination and coupling withISA to produce 0.41 g of1-(2-phthalimidylethyl)-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazolewhich was refluxed with 0.3 ml of hydrazine in 20 ml of MeOH for 0.5 hto yield the desired product (0.31 g, 0.96 mmol, 68% overall). Theproduct obtained was converted to the fumarate salt and recrystallizedfrom isopropanol to afford 0.21 g (24%) of the product as a white foamysolid.

EXAMPLE 41

[0149] 2-Methyl-5-(2-imidazolin-2-ylamino)benzimidazole (#41)

[0150] 2-Methyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (1.0 g, 6.5 mmol) in 20 ml of AcOH wasstirred at reflux for 12 h. Reaction mixture was concentrated in vacuoto yield a dark brown residue, which, in spectroscopic analysis,corresponds to 2-methyl-5-nitrobenzimidazole and was subjected to afollowing reaction without further purification. The nitrobenzimidazoleand 50 mg of 10% Pd/C were dissolved in 100 ml of MeOH and stirred for12 h under H₂. The reaction mixture was filtered and concentrated invacuo yielding 0.95 g (6.5 mmol, >95%) of brown oil which was identifiedas 2-methyl-5-aminobenzimidazole in NMR and used in a following reactionwithout further purification.

[0151] 2-Methyl-5-(2-imidazolin-2-ylamino)benzimidazole. A solution ofthe amine (0.70 g, 4.7 mmol) and ISA (0.8 g, 5.9 mmol) was stirred atreflux for 12 h. The reaction mixture was concentrated in vacuo to yieldan oily residue which was subjected to silica gel column chromatography(NH₃ sat'd 20% MeOH/EtOAc) to yield 0.81 g (3.8 mmol, 81%) of thedesired product.

EXAMPLE 42

[0152] 2-Methyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#42)

[0153] 2-Methyl-4-bromo-5-aminobenzimidazole. To a solution of 0.9 g(6.1 mmol) of 2-methyl-5-aminobenzimidazole in 50 ml of AcOH was added0.16 ml of Br₂ (3.1 mmol) dropwise and resulting reaction mixture wasstirred for 1 h at 25° C. Reaction mixture was concentrated in vacuo andpurified on silica gel column chromatography (20% Isopropanol/EtOAC) toyield 0.56 g (2.5 mmol, 41%) of the desired product.

[0154] 2-Methyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Theamine (0.56 g, 2.5 mmol) and ISA (1.0 g, 7.4 mmol) were dissolved in 5ml of isobutanol and stirred at reflux for 12 h. The reaction mixturewas concentrated in vacuo and subjected to column chromatography (NH₃sat'd 20% Isopropanol/EtOAC) to yield 0.72 g (2.4 mmol, >99%) of theproduct. The product obtained was converted to the fumarate salt andrecrystallized from MeOH to afford 0.25 g (25%) of the product as awhite crystal: mp 222-224° C.; Anal. Calc. forC₁₁H₁₂N₅Br.1.0C₄H₄O₄.0.5H₂O requires C, 42.98; H, 4.09; N, 16.71. Found:C, 43.14; H, 4.03; N, 16.33.

EXAMPLE 43

[0155] 2-Ethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#43)

[0156] 2-Ethyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (1.0 g, 6.5 mmol) in 20 ml of propionicacid was stirred at reflux for 12 h. Reaction mixture was concentratedin vacuo to yield a dark brown residue, which, in spectroscopicanalysis, corresponds to 2-ethyl-5-nitrobenzimidazole and was subjectedto a following reaction without further purification. Thenitrobenzimidazole and 50 mg of 10% Pd—C were dissolved in 100 ml ofMeOH and stirred for 12 h under H₂. The reaction mixture was filteredand concentrated in vacuo yielding 0.95 g (6.5 mmol, >95%) of brown oilwhich was identified as 2-ethyl-5-aminobenzimidazole in NMR and used ina following reaction without further purification.

[0157] 2-Ethyl-4-bromo-5-aminobenzimidazole. To a solution of 1.3 g (7.7mmol) of 2-ethyl-5-aminobenzimidazole in 50 ml of AcOH was added 0.40 mlof Br₂ (7.5 mmol) dropwise and resulting reaction mixture was stirredfor 1 h at 25° C. The reaction mixture was concentrated in vacuo andpurified on silica gel column chromatography (20% isopropanol/EtOAC) toyield 1.5 g (6.3 mmol, 82%) of the desired product.

[0158] 2-Ethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of 2-ethyl-4-bromo-5-aminobenzimidazole (1.5 g, 6.3 mmol) withISA (2.3 g, 17 mmol) provides 1.4 g (4.5 mmol, 71%) of the desiredproduct. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 1.53 g (61%) of the product asa white solid: mp 186-187° C.; Anal. Calc. for C₁₂H₁₄N₅Br.1.0C₄H₄O₄requires C, 45.30; H, 4.28; N, 16.51. Found: C, 45.03; H, 4.11; N,16.88.

EXAMPLE 44

[0159] 2-Isopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#44)

[0160] 2-Isopropyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (0.9 g, 5.9 mmol) in 5 ml of isobutyricacid was stirred at reflux for 12 h. The reaction mixture wasconcentrated in vacuo to yield a dark brown residue, which was dissolvedin 100 ml of EtOAc and washed with aqueous NaHCO₃. Organic layer wasdried over MgSO₄ and concentrated in vacuo, yielding an oil which wascharacterized as 2-isopropyl-5-nitrobenzimidazole and subjected to afollowing reaction without further purification. The nitrobenzimidazoleand 50 mg of 10% Pd—C were dissolved in 100 ml of MeOH and stirred for12 h under H₂. The reaction mixture was filtered and concentrated invacuo, yielding 0.95 g (5.4 mmol, 92%) of the desired product.

[0161] 2-Isopropyl-4-bromo-5-aminobenzimidazole. To a solution of 0.95 g(5.4 mmol) of 2-isopropyl-5-aminobenzimidazole in 50 ml of AcOH wasadded 0.19 ml (3.7 mmol) of Br₂ dropwise and resulting reaction mixturewas stirred for 1 h at 25° C. Reaction mixture was concentrated in vacuoand purified on silica gel column chromatography (5% MeOH/EtOAC) toyield 0.89 g (3.5 mmol, 95%) of the desired product.

[0162] 2-Isopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the bromoamine (0.89 g, 3.5 mmol) and ISA (1.5 g, 11 mmol)provides 0.42 g (1.3 mmol, 37%) of the expected product. The productobtained was converted to the fumarate salt and recrystallized from EtOHto afford 0.43 g (28%) of the product as a light gray solid: mp 176-178°C.; Anal. Calc. for C₁₃H₁₆N₅Br.1.0C₄H₄O₄ requires C, 46.59; H, 4.60; N,15.98. Found: C, 45.14; H, 4.39; N, 15.78.

EXAMPLE 45

[0163] 2-tert-Butyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#45)

[0164] 2-tert-Butyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (2.0 g, 13 mmol) in 10 ml oftrimethylacetic acid was stirred at reflux for 12 h. Reaction mixturewas concentrated in vacuo to yield a oil which was subjected to columnchromatography (CHCl₃, neat) to yield 2.2 g (10 mmol, 77%) of2-tert-butyl-5-nitrobenzimidazole. The nitrobenzimidazole and 0.5 g of10 Pd—C were dissolved in 100 ml of MeOH and stirred for 12 h under H₂.The reaction mixture was filtered and concentrated in vacuo to provide1.9 g (10 mmol, >95%) of the desired product.

[0165] 2-tert-Butyl-4-bromo-5-aminobenzimidazole. To a solution of 0.53g (2.8 mmol) of 2-tert-butyl-5-aminobenzimidazole in 50 ml of AcOH wasadded 0.05 ml (1.0 mmol) of Br₂ dropwise and resulting reaction mixturewas stirred for 1 h at 25° C. Reaction mixture was concentrated in vacuoand purified on silica gel column chromatography (CHCl₃, neat) to yield0.18 g (0.67 mmol, 67%) of the desired product.

[0166] 2-tert-Butyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the bromoamine (0.18 g, 0.67 mmol) and ISA (0.30 g, 2.2mmol) provides 0.21 g (0.62 mmol, 93%) of the product. The productobtained was converted to the fumarate salt and recrystallized from EtOHto afford 0.43 g (28%) of the product as a light gray solid: mp 176-178°C.; Anal. Calc. for C₁₄H₁₈N₅Br.1.0C₄H₄O₄ requires C, 47.48; H, 4.90; N,15.48. Found: C, 45.14; H, 4.39; N, 15.78.

EXAMPLE 46

[0167] 2-Trifluoromethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#46)

[0168] 2-Trifluoromethyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (3.0 g, 20 mmol) in 15 ml oftrifluoroacetic acid was stirred at reflux for 12 h. The reactionmixture was concentrated in vacuo to yield a oily residue, which wasdissolved in 100 ml of EtOAc and washed with aqueous NaHCO₃. The organiclayer was dried over MgSO₄ and concentrated in vacuo to provide an oilwhich was characterized as 2-trifluromethyl-5-nitrobenzimidazole andsubjected to the following reaction without further purification. Thenitrobenzimidazole and 500 mg of 10% Pd—C were dissolved in 100 ml ofMeOH and stirred for 12 h under H₂. The reaction mixture was filteredand concentrated in vacuo, yielding 3.2 g (16 mmol, 80%) of the desiredproduct.

[0169] 2-Trifluoromethyl-4-bromo-5-aminobenzimidazole. To a solution of3.2 g (16 mmol) of 2-trifluoromethyl-5-aminobenzimidazole in 50 ml ofAcOH was added 0.34 ml (6.6 mmol) of Br₂ dropwise and resulting reactionmixture was stirred for 1 h at 25° C. The reaction mixture wasconcentrated in vacuo and purified on silica gel column chromatography(10% MeOH/CHCl₃) to yield 1.7 g (6.2 mmol, 94%) of the desired product.

[0170]2-Trifluoromethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole.Reaction of the bromoamine (1.3 g, 4.6 mmol) and ISA (1.5 g) provided0.39 g (1.1 mmol, 23%) of the desired product. The product obtained wasconverted to the fumarate salt and recrystallized from EtOH to afford0.40 g (21%) of the product as a light brown solid: mp 231-232° C.

EXAMPLE 47

[0171] 2-Cyclopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#47)

[0172] 2-Cyclopropyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (1.0 g, 6.6 mmol) in 15 ml ofcyclopropanecarboxylic acid was stirred at reflux for 12 h. The reactionmixture was concentrated in vacuo to yield a oil, which was dissolved in100 ml of EtOAc and washed with aqueous NaHCO₃. Organic layer was driedover MgSO₄ and concentrated in vacuo, yielding an oil which wascharacterized as 2-cyclopropyl-5-nitrobenzimidazole and subjected to afollowing reaction without further purification. The nitrobenzimidazoleand 50 mg of 10% Pd—C were dissolved in 100 ml of MeOH and stirred for12 h under H₂. The reaction mixture was filtered and concentrated invacuo to provide 0.87 g (4.9 mmol, 75%) of the desired product.

[0173] 2-Cyclopropyl-4-bromo-5-aminobenzimidazole. To a solution of 0.87g (4.9 mmol) of 2-cyclopropyl-5-aminobenzimidazole in 50 ml of AcOH wasadded 0.10 ml (1.9 mmol) of Br₂ dropwise and resulting reaction mixturewas stirred for 1 h at 25° C. The reaction mixture was concentrated invacuo and purified on silica gel column chromatography (5% MeOH/EtOAC)to yield 0.42 g (1.8 mmol, >95%) of the desired product.

[0174] 2-Cyclopropyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole. Areaction of the bromoamine (0.69 g, 2.4 mmol) and ISA (1.1 g, 8.2 mmol)provides 0.71 g (2.2 mmol, 92%) of the desired product. The productobtained was converted to the fumarate salt and recrystallized fromisobutanol to afford 0.62 g (62%) of the product as a light yellowsolid: mp 81-83° C.; Anal. Calc. for C₁₂H₁₄N₅Br.1.0C₄H₄O₄.1.0H₂Orequires C, 44.95; H, 4.44; N, 15.42. Found: C, 45.28; H, 4.35; N,14.94.

EXAMPLE 48

[0175] 2-Diphenylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole(#48)

[0176] 2-Diphenylmethyl-5-aminobenzimidazole. A solution of4-nitro-1,2-phenylenediamine (2 g, 13 mmol) in 10 g of diphenylaceticacid(neat) was stirred at reflux for 12 h. Reaction mixture wasconcentrated In Vacuo to yield a dark brown residue, which was dissolvedin 100 ml of EtOAc and washed with aqueous NaHCO₃. Organic layer wasdried over MgSO₄ and concentrated in vacuo, yielding an oil which waspurified on column chromatography (50% Hexane/EtOAc) to yield 1.7 g (5.3mmol, 39%) of 2-diphenylmethyl-5-nitrobenzimidazole. Thenitrobenzimidazole and 250 mg of 10% Pd-C were dissolved in 100 ml ofMeOH and stirred for 12 h under H₂. The reaction mixture was filteredand concentrated in vacuo to provide 1.4 g (5.2 mmol, >95%) of thedesired product.

[0177] 2-Diphenylmethyl-4-bromo-5-aminobenzimidazole. To a solution of1.1 g (3.7 mmol) of 2-diphenylmethyl-5-aminobenzimidazole in 50 ml ofAcOH was added 0.07 ml (1.3 mmol) of Br₂ dropwise and resulting reactionmixture was stirred for 1 h at 25° C. Reaction mixture was concentratedin vacuo and purified on silica gel column chromatography (5%MeOH/EtOAC) to yield 0.42 g (1.1 mmol, 86%) of the desired product.

[0178] 2-Diphenylmethyl-4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole.A reaction of the amine (1.1 g, 2.9 mmol) and ISA (1.5 g, 11 mmol)produces 0.51 g (1.1 mmol, 39%) of the expected product. The productobtained was converted to the fumarate salt and recrystallized from MeOHto afford 0.31 g (21%) of the product as a light brown solid: mp240-242° C.; Anal. Calc. for C₂₃H₂₀N₅Br.1.0C₄H₄O₄ requires C, 57.66; H,4.30; N, 12.45. Found: C, 57.58; H, 4.12; N, 12.28.

EXAMPLE 49

[0179] 6-Methyl-5-(2-imidazolin-2-ylamino)benzimidazole (#49)

[0180] 6-Methyl-5-aminobenzimidazole. To a solution of 20 ml of fumingnitric acid was added 5-methylbenzimidazole (1.6 g, 12 mmol) slowly over0.5 h and reaction mixture was stirred for 3 h at −15° C. Duringaddition of substrate, reaction temperature was kept below −10° C.Sticky reaction mixture was then poured into ice water to form a yellowprecipitation, which was collected and dried in vacuo to provide 0.37 g(2.1 mmol, 17%) of 5-methyl-6-nitrobenzimidazole. The nitrobenzimidazolewas converted to the corresponding amine (0.32 g, 95%) on hydrogenation(H₂, Pd/C).

[0181] 6-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole. The amineobtained above was stirred at reflux with ISA (0.96 g, 7.2 mmol) inisobutanol for 12 h. Column chromatographic separation of reactionmixture (NH₃ sat'd 30% MeOH/EtOAc) produced 0.40 g (1.6 mmol, 78%) ofthe desired product. The product obtained was converted to the fumaratesalt and recrystallized from EtOH to afford 0.43 g (63%) of the productas a white solid: mp 219-221° C; Anal. Calc. for C₁₁H₁₃N₅.1.0C₄H₄O₄requires C, 54.38; H, 5.17; N, 21.14. Found: C, 54.14; H, 5.33; N,20.84.

EXAMPLE 50

[0182] 4,6-Dibromo-5-(2-imidazolin-2-ylamino)benzimidazole (#50). To asolution of 4-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (0.2 g, 0.7mmol) in 10 ml AcOH was added 200 mg of Hg(OAc)₂ and few drops of Br₂.Reaction mixture was concentrated in vacuo, yielding a dark oilyresidue, which was subjected to silica gel column chromatography (NH₃sat'd 30% MeOH/EtOAc) to provide 210 mg (0.58 mmol, 86%) of the desiredproduct. The product obtained was converted to the fumarate salt andrecrystallized from EtOH to afford 0.051 g (14%) of the product as awhite solid.

EXAMPLE 51

[0183] 7-Bromo-5-(2-imidazolin-2-ylamino)benzimidazole (#51)

[0184] 2,4-Dinitro-6-bromoaniline. To a solution of 2,4-dinitroaniline(2.2 g, 12 mmol) in 40 ml of AcOH was added 1.0 ml of Br₂ dropwise andreaction mixture was stirred for 1 h. The reaction mixture wasconcentrated in vacuo, yielding a dark residue which was diluted withEtOAc and washed with aqueous NaHCO₃. Organic layer was dried over MgSO₄and concentrated in vacuo to provide 2.9 g (11 mmol, 92%) of2,4-dinitro-6-bromo-aniline which was characterized by NMR and used in afollowing reaction without further purification.

[0185] 4-Bromo-6-aminobenzimidazole. A solution of 4.0 g of SnCl₂₀.2H₂Oand 15 ml of HCl was added into 2,4-dinitro-6-bromoaniline (1.8 g, 6.9mmol) and resulting reaction mixture was stirred for 2 h at 25° C. Thereaction mixture was then basified by adding 15% aq. NaOH and extractedwith CHCl₃ several times. Combined extracts were dried over MgSO₄ andconcentrated in vacuo to produce 1.4 g (>95%) of corresponding amine.The amine was stirred at reflux in 10 ml of formic acid and 10 ml ofacetic anhydride for 12 h. The reaction mixture was concentrated invacuo, yielding oily residue which was stirred in 30 ml of HCl sat'dEtOH for 0.5 h. The oily reaction mixture after concentration wassubjected to column chromatography (5% NH₃ sat'd MeOH/EtOAc) to yield1.3 g (>95%) of the desired product.

[0186] 7-Bromo-5-(2-imidazolin-2-ylamino)benzimidazole.

[0187] 4-bromo-6-aminobenzimidazole (0.4 g, 1.9 mmol) and ISA (1.2 g,8.9 mmol) was dissolved in isobutanol and stirred at reflux for 12 h.Column chromatographic separation of the reaction mixture (NH₃ sat'd 20%MeOH/EtOAc) provided 0.41 g (1.5 mmol, 78%) of the product. The productobtained was converted to the fumarate salt and recrystallized fromisopropanol to afford 0.24 g (32%) of the product as a light brownsolid: mp 217-218° C.; Anal. Calc. for C₁₀H₁₀N₅Br.1.0CH₄O₄ requires C,42.44; H, 3.56; N, 17.68. Found: C, 42.28; H, 3.58; N, 17.40.

EXAMPLE 52

[0188] 7-Methyl-5-(2-imidazolin-2-ylamino)benzimidazole (#52)

[0189] 4-Methyl-6-aminobenzimidazole. To the solution of4-bromo-6-aminobenzimidazole (0.85 g, 6.0 mmol) in sealed tube with 10ml of DMF was added tetramethyltin (1.7 ml, 12 mmol) andbis(triphenylphosphine)palladium(II) chloride (0.20 g). The resultingreaction mixture was stirred for 12 h at 140° C. and concentrated invacuo, yielding oily residue which was subjected to columnchromatography (5% MeOH/CHCl₃)to produce 0.28 g (45%) of the desiredproduct.

[0190] 7-Methyl-S-(2-imidazolin-2-ylamino)benzimidazole. A solution ofthe amine (0.28 g, 1.8 mmol) and ISA (0.82 g, 6.2 mmol) was stirred atreflux for 24 h. The reaction mixture was subjected to columnchromatography (30% NH₃ sat'd MeOH/EtOAc) to yield 0.23 g (57%) of theproduct. The product obtained was converted to the fumarate salt andrecrystallized from isopropanol to afford 0.24 g (40%) of the product asa light brown solid: mp 229-231° C.; Anal. Calc. for C₁₁H₁₃N₅.1.0C₄H₄O₄requires C, 54.38; H, 5.17; N, 21.14. Found: C, 54.02; H, 5.15; N,20.48.

EXAMPLE 53

[0191] 7-Chloro-5-(2-imidazolin-2-ylamino)benzimidazole (#53)

[0192] 4-chloro-6-aminobenzimidazole. Methanolic solution of6-chloro-2,4-dinitroaniline (2.4 g, 11 mmol) was stirred overnight with100 mg of 10% Pd/C under H₂. Reaction mixture was filtered andconcentrated in vacuo to provide an oil which was dissolved in 10 ml ofacetic anhydride and 10 ml of formic acid and stirred at reflux for 12h. The reaction mixture was concentrated in vacuo, yielding a brown oilwhich was characterized as 4-chloro-6-foramidylbenzimidazole in NMRanalysis. The foramide was dissolved in 20 ml of HCl sat'd EtOH andstirred for 3 h at 25° C. The reaction mixture was purified in columnchromatography (5% MeOH/EtOAc) to provide 0.89 g (5.3 mmol, 48% overall)of the desired product.

[0193] 7-Chloro-5-(2-imidazolin-2-ylamino)benzimidazole. A solution of4-chloro-6-aminobenzimidazole (0.9 g, 5.4 mmol) and ISA (1.7 g, 13 mmol)was stirred at reflux for 24 h. Column chromatographic separation ofreaction mixture (30% NH₃ sat'd MeOH/EtOAc) provided 0.53 g (2.2 mmol,41%) of the product. The product obtained was converted to the fumaratesalt and recrystallized from MeOH to afford 0.41 g (22%) of the productas a light brown solid: mp 220-221° C.; Anal. Calc. forC₁₀H₁₀N₅Cl.1.0C₄H₄O₄ requires C, 47.81; H, 4.01; N, 19.91. Found: C,46.03; H, 4.14; N, 19.64.

EXAMPLE 54

[0194] 7-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole (#54)

[0195] 2,4-Dinitro-6-iodoaniline. To a solution of 2,4-dinitroaniline(3.0 g, 16 mmol) and Hg(OAc)₂ (6.8 g, 21 mmol) in 40 ml of AcOH wasadded 5.0 g (19 mmol) of 12 in 100 ml of AcOH dropwise and reactionmixture was stirred for 12 h. The reaction mixture was concentrated invacuo, yielding a dark residue which was diluted with EtOAc and washedwith aqueous NaHCO₃. Organic layer was dried over MgSO₄ and concentratedin vacuo to produce dark residue which was subjected to columnchromatography (CHCl₃, neat) to provide 4.1 g (13 mmol, 81%) of2,4-dinitro-6-iodoaniline.

[0196] 7-Iodo-5-aminobenzimidazole. A solution of 10 g of SnCl₂₀.2H₂Oand 20 ml of HCl was added into 2,4-dinitro-6-iodoaniline (4.1 g, 13mmol) and resulting reaction mixture was stirred at reflux for 48 h. Thereaction mixture was then basified by adding 15% aq. NaOH and extractedwith CHCl₃ several times. Combined extracts were dried over MgSO₄ andconcentrated in vacuo, yielding oily residue which was subjected tocolumn chromatography (5% MeOH/EtOAc) to yield 1.1 g (4.4 mmol, 0.33%)of the amine. The amine was stirred at reflux in 10 ml of formic acidand 10 ml of acetic anhydride for 12 h. The reaction mixture wasconcentrated in vacuo to yield an oily residue which was stirred in 30ml of HCl sat'd EtOH for 2 h. The oily reaction mixture afterconcentration was subjected to column chromatography (5% NH₃ sat'dMeOH/EtOAc) to provide 0.69 g (2.7 mmol, 60%) of the desired product.

[0197] 7-Iodo-5-(2-imidazolin-2-ylamino)benzimidazole. A solution of4-iodo-6-aminobenzimidazole (0.69 g, 2.7 mmol) and ISA (0.90 g, 6.7mmol) was stirred at reflux for 12 h. Column chromatographic separation(30% NH₃ sat'd MeOH/EtOAC) of resulting reaction mixture provided 0.88 g(>99%) of the product. The product obtained was recrystallized fromisopropanol to afford 0.56 g (64%) of the product as a light brownsolid: mp 180-181° C.

EXAMPLE 55

[0198] 7-Ethyl-5-(2-imidazolin-2-ylamino)benzimidazole (#55)

[0199] 2,4-Diamino-6-ethylaniline. A solution of2,4-dinitro-6-bromoaniline (1.6 g, 6.1 mmol), tetraethyltin (2.4 ml,12.2 mmol) and Cl₂Pd(PPh₃)₂ (100 mg) in 10 ml of DMF was stirred at 140°C. for 12 h. Reaction mixture was concentrated in vacuo, yielding an oilwhich was purified on silica gel column chromatography (CH₂Cl₂, neat) toprovide 0.68 g (3.2 mmol, 53%) of 2,4-dinitro-6-ethylaniline, which wasconverted to the diamine (0.45 g, 95%) on hydrogenation (H₂/Pd—C).

[0200] 7-Ethyl-5-aminobenzimidazole. The amine (0.46 g, 3.1 mmol) wasstirred at reflux in formic acid for 12 h. The reaction mixture wasconcentrated in vacuo to provide an oil, which was disolved in 50 ml ofHCl sat'd EtOH and stirred for 1 h. The reaction mixture wasconcentrated in vacuo, yielding an oil, which was subjected to columnchromatography (EtOAc, neat) to provide 0.23 g (1.5 mmol, 47%) of thedesired product.

[0201] 7-Ethyl-S-(2-imidazolin-2-ylamino)benzimidazole. Thebenzimidazole (0.23 g, 1.5 mmol) and ISA (0.67 g, 5.0 mmol) wasdissolved in isobutanol and stirred at reflux for 12 h. Columnchromatographic separation of reaction mixture (NH₃ sat'd 20%MeOH/EtOAc) provided 0.30 g (1.4 mmol, 92%) of the product. The productobtained was converted to the fumarate salt and recrystallized fromisopropanol to afford 0.17 g (46%) of the product as a light brownsolid: mp 203-205° C.; Anal. Calc. for C₁₂H₁₅N₅.1.0C₄H₄O₄ requires C,55.65; H, 5.55; N, 20.28. Found: C, 55.90; H, 5.43; N, 19.87.

EXAMPLE 56

[0202] 7-Butyl-5-(2-imidazolin-2-ylamino)benzimidazole (#56)

[0203] 2,4-Diamino-6-butylaniline. A solution of2,4-dinitro-6-bromoaniline (2.0 g, 7.6 mmol), tetrabutyltin (5.3 ml,15.2 mmol) and Cl₂Pd(PPh₃)₂ (100 mg) in 10 ml of DMF was stirred at 140°C. for 12 h. Reaction mixture was concentrated in vacuo, yielding an oilwhich was purified on silica gel column chromatography (CH₂Cl₂, neat) toprovide 0.50 g (2.0 mmol, 27%) of 2,4-dinitro-6-butylaniline, which wasconverted to the diamine (0.38 g, >95%) on hydrogenation (H₂/Pd—C).

[0204] 7-Butyl-5-aminobenzimidazole. The amine (0.46 g, 3.1 mmol) wasstirred at reflux in formic acid for 12 h. reaction mixture wasconcentrated in vacuo to provide an oil, which was dissolved in 50 ml ofHCl sat'd EtOH and stirred for 1 h. The reaction mixture wasconcentrated in vacuo, yielding an oil, which was subjected to columnchromatography (EtOAc, neat) to provide 0.11 g (0.86 mmol, 28%) of thedesired product.

[0205] 7-Butyl-5-(2-imidazolin-2-ylamino)benzimidazole. Thebenzimidazole (0.11 g, 0.86 mmol) and ISA (0.25 g, 1.9 mmol) wasdissolved in isobutanol and stirred at reflux for 12 h. Columnchromatographic separation of reaction mixture (NH₃ sat'd 20%MeOH/EtOAc) provided 0.21 g (0.81 mmol, 95%) of the product. The productobtained was converted to the fumarate salt and recrystallized fromisopropanol to afford 0.17 g (45%) of the product as a light brownsolid: mp 115-117° C.; Anal. Calc. for C₁₄H₁₉N₅.1.5C₄H₄,₄ requires C,55.68; H, 5.84; N, 16.23. Found: C, 54.90; H, 5.84; N, 15.99.

EXAMPLE 57

[0206] 7-Phenyl-5-(2-imidazolin-2-ylamino)benzimidazole (#57)

[0207] 2,4-Diamino-6-phenylaniline. A solution of2,4-dinitro-6-bromoaniline (2.5 g, 9.5 mmol), tetraphenylltin (6.1 g,14.3 mmol) and Cl₂Pd(PPh₃)₂ (100 mg) in 10 ml of DMF was stirred at 140°C. for 12 h. Reaction mixture was concentrated in vacuo, yielding an oilwhich was purified on silica gel column chromatography (CH₂Cl₂, neat) toprovide 1.0 g (3.8 mmol, 41%) of 2,4-dinitro-6-phenylaniline, which wasconverted to the diamine (0.72 g, >95%) on hydrogenation (H₂/Pd—C).

[0208] 7-Phenyl-5-aminobenzimidazole. The amine (0.72 g, 3.8 mmol) wasstirred at reflux in formic acid for 12 h. The reaction mixture wasconcentrated in vacuo to provide an oil, which was dissolved in 50 ml ofHCl sat'd EtOH and stirred for 1 h. The reaction mixture wasconcentrated in vacuo, yielding an oil, which was subjected to columnchromatography (EtOAc, neat) to provide 0.48 g (2.3 mmol, 60%) of thedesired product.

[0209] 7-Phenyl-5-(2-imidazolin-2-ylamino)benzimidazole. Thebenzimidazole (0.48 g, 2.3 mmol) and ISA (1.0 g, 7.5 mmol) was dissolvedin isobutanol and stirred at reflux for 12 h. Column chromatographicseparation of reaction mixture (NH₃ sat'd 20% MeOH/EtOAc) provided 0.64g (0.23 mmol, >95%) of the product. The product obtained was convertedto the fumarate salt and recrystallized from isopropanol to afford 0.25g (24%) of the product as a light brown solid: mp 149-151° C.; Anal.Calc. for C₁₆H₁₅N₅.1.5C₄H₄O₄ requires C, 58.53; H, 4.69; N, 15.51.Found: C, 57.79; H, 4.80; N, 15.31.

EXAMPLE 58

[0210] 4,7-Dibromo-5-(2-imidazolin-2-ylamino)benzimidazole (#58) To asolution of 7-bromo-5-(2-imidazolin-2-ylamino)benzimidazole (0.6 g, 2.1mmol) in 10 ml of AcOH was added Br₂ (0.057 ml, 1.1 mmol) in a portion.The resulting reaction mixture was stirred for 1 h at 25° C.Concentration of reaction mixture in vacuo yields a brown oil which wassubjected to column chromatography (30% NH₃ sat'd MeOH/EtOAc) toprovides 0.28 g (1.5 mmol, 71%) of the desired product. The productobtained was recrystallized from MeOH to afford 0.22 g (56%) of theproduct as a light brown solid: mp 320-321° C.; Anal. Calc. forC₁₀H₉N₅Br₂.requires C, 33.45; H, 2.53; N, 19.51. Found: C, 33.93; H,4.05; N, 19.01.

EXAMPLE 59

[0211] 4-Bromo-7-methyl-5-(2-imidazolin-2-ylamino)benzimidazole (#59)

[0212] 4-Bromo-7-methyl-5-aminobenzimidazole. A solution of4,7-dibromo-5-aminobenzimidazole (1.5 g, 5.1 mmol) in 10 ml of DMF wastransferred into pressure bottle under Ar₂. To the solution was addedtetramethyltin (3.6 ml, 20 mmol) andbis(triphenylphosphine)palladium(II) chloride (200 mg). The resultingreaction mixture was stirred at 140° C. for 24 h and concentrated invacuo, yielding a dark oil which was subjected to column chromatography(40% EtOAC/CHCl₃) to yield 0.34 g (1.5 mmol, 29%) of the desired productas well as 0.75 g of 4,7-dimethyl-5-aminobenzimidazole.

[0213] 4-Bromo-7-methyl-5-(2-imidazolin-2-ylamino)benzimidazole. Asolution of the amine (0.34 g, 1.5 mmol) and ISA (0.69 g, 5.1 mmol) in10 ml of isobutanol was stirred at reflux for 12 h. The resultingreaction mixture was purified on column chromatography (30% NH₃ sat'dMeOH/EtOAc) to yield 0.25 g (0.86 mmol, 57%) of the desired product. Theproduct obtained was recrystallized from MeOH to afford 0.13 g (30%) ofthe product as a light brown solid: mp 242-244° C.; Anal. Calc. forC₁₁H₁₂N₅Br requires C, 44.91; H, 4.11; N, 23.81. Found: C, 43.93; H,4.05; N, 23.01.

EXAMPLE 60

[0214] 4-Bromo-7-chloro-5-(2-imidazolin-2-ylamino)benzimidazole (#60).To a solution of 7-chloro-5-(2-imidazolin-2-ylamino)benzimidazole (0.61g, 2.6 mmol) in 10 ml of AcOH was added 0.3 ml of Br₂. Resultingreaction mixture was stirred for 12 h at 25° C. and concentrated invacuo, yielding an oil, which was subjected to column chromatography(NH₃ sat'd 30% MeOH/EtOAc) to yield 0.23 g (0.85 mmol, 33%) of thedesired product. The product obtained was converted to the fumarate saltand recrystallized from MeOH to afford 0.12 g (12%) of the product as alight yellow solid: mp 244-246° C.; Anal. Calc. forC₁₀H₉N₅BrCl.1.0C₄H₄O₄.0.5H₂O requires C, 37.77; H, 3.17; N, 18.35.Found: C, 37.75; H, 3.08; N, 18.21.

[0215] Pharmacological Profiles of the Compounds in Cloned HumanAdrenergic Receptors.

[0216] Binding and functional assays were performed using stablytransfected human alpha adrenergic receptors. Equilibrium competitionbinding assays were performed with membrane preparations from culturedLM(tk−) cells stably transfected with the cloned human adrenoceptorsubtypes except for α_(2b), which was expressed in Y-1 cells, using[³H]prazosin for α₁ receptors and [3H]rauwolscine for α₂ receptors.

EXAMPLE 61

[0217] Protocol for the Determination of the Potency of α₂ Agonists

[0218] The activity of the compounds at the different receptors wasdetermined in vitro using cultured cell lines that selectively expressthe receptor of interest. These cell lines were prepared by transfectingthe cloned cDNA or cloned genomic DNA or constructs containing bothgenomic DNA and cDNA encoding the human alpha adrenergic receptors asdescribed below. Table 1 shows the binding and functional activities atcloned human alpha adrenergic receptors.

[0219] α_(2A) Human Adrenergic Receptor: The entire coding region ofα_(2A) (1350 bp), including 1.0 kilobasepairs of 5′ untranslatedsequence (5′UT) and 100 bp of 3′ untranslated sequence (3′UT), wascloned into the Smal site of the eukaryotic expression vector pCEXV-3.The insult housing this coding region was an @ 2.5 kb Kpnl/HindIII humanplacenta genomic fragment which was end-blunted by either T₄ polymeraseor Klenow fragment of DNA polymerase. Stable cell lines were obtained bycotransfection with the Plasmid pGCcos3neo (plasmid containing theα_(2A) receptor gene) and the plasmid pGCcos3neo (plasmid containing theaminoglycoside transferase gene) into LM(tk−), CHO, and NIT3T3 cells,using calcium phosphate technique. The cells were grown, in a controlledenvironment (37° C., 5% CO₂), as monolayers in Dulbecco's modifiedEagle's Medium (GIBCO, Grand Island, N.Y.) containing 25 mM glucose andsupplemented with 10% bovine calf serum, 100 units/ml penicillin g, and100 μg/ml streptomycin sulfate. Stable clones were then selected forresistance- to the antibiotic G-418 (1 mg/ml), and membranes wereharvested and assayed for their ability to bind [³H]rauwolscine asdescribed below (see “Radioligand Binding Assays”)

[0220] α_(2B) Human Adrenergic Receptor: The entire coding region ofα_(2B) (1350 bp), including 393 bp of 5′untranslated sequence and 11 bpof 3′ untranslated sequence, was cloned into the eukaryotic expressionvector pcEXV-3 (Weinshank et al, U.S. Pat. No. 5,053,337, issued Oct. 1,1991). Stable cell lines were selected as described above.

[0221] α_(2C) Human Adrenergic Receptor: The entire coding region ofα_(2C) (1383 bp), including 2 bp of 5′ UT and 400 bp of 3′ UT, wascloned into the Smal site of the eukaryotic expression vector pCEXV-3.The insert housing this coding region was an @1.8 kb NcoI/EcoRI humanspleen genomic fragment which was end-blunted by either T₄ polymerase orKlenow fragment of DNA polymerase. Stable cell lines were selected asdescribed above.

[0222] Radioligand Binding Assays: Transfected cells from culture flaskswere scraped into 5 ml of 5 mM Tris-HCl, 5 mM EDTA, pH 7.5, and lysed bysonication. The cell lysates were centrifuged at 1000 rpm for 5 min at4° C., and the supernatant was centrifuged at 30,000×g for 20 min at 4°C. The pellet was suspended in 50 mM Tris-HCl, 1 mM MgCl₂, and 0.1%ascorbic acid at pH 7.5. Binding of α₂ antagonist [³H]rauwolscine (0.5mM) to membrane preparations of LM(tk−) cells was done in a final volumeof 0.25 ml and incubated at 37° C. for 20 min. Nonspecific binding wasdetermined in the presence of 10 μM phentolamine. The reaction wasstopped by filtration through GF/B filters using a cell harvester.Inhibition experiments, routinely consisting of 7 concentrations of thetested compounds, were analyzed using a non-linear regressioncurve-fitting computer program to obtain Ki values.

[0223] Measurement of Agonist Activity: The agonist activity (expressedas pEC₅₀) was measured as a function of the ability to inhibit theforskolin-stimulated synthesis of cyclic adenosine monophosphate (cAMP).The stably transfected cells were incubated in Ham's F10 with 5 mMtheophylline, 10 mM HEPES, 10 μM pargyline, and/or appropriateconcentrations of forskolin for 20 min at 37° C. in 5% CO₂. The testedcompounds were then added to a final concentration of 0.001 μM to 1 μMand incubated for an additional 15 min at 37° C. in 5% CO₂. The mediumwas aspirated and the reaction was stopped by the addition of 100 mMHCl. To demonstrate competitive antagonism, a dose-response curve fornorepinephrine was measured in parallel, using a fixed dose ofnorepinephrine(0.32 μM). The plates are stored at 4° C. for 15 min andassayed to determine the linear concentration of cAMP. The appropriatedilution is interpolated from the standard curve of cold cAMP. Theassessment of cAMP formation is determined by radioimmunoassay (cAMPradioimmunoassay kit; Advanced Magnetics, Cambridge, Mass.).Radioactivity was quantified using a Packard COBRA Auto Gamma counter,equipped with data reduction software.

[0224] α_(1A) Human Adrenergic Receptor: The entire coding region ofα_(1A) (1719 bp), including 150 bp of 5′ untranslated sequence (5′UT)and 300 bp of 3′ untranslated sequence (3′UT), was cloned into the BamHIand ClaI sites of the polylinker-modified eukaryotic expression vectorpCEXV-3, called EXJ.HR (Bard et al, International Publication No. WO94/08040, published Apr. 14, 1994). The construct involved the ligationof partial overlapping human lymphocyte genomic and hippocampal cDNAclones: 5′ sequences were contained on a 1.2 kb SmaI-XhoI genomicfragment (the vector-derived BamHI site was used for subcloning insteadof the internal insert-derived SmaI site) and 3′ sequences werecontained on 1.3 kb XhoI-ClaI cDNA fragment (the ClaI site was from thevector polylinker). Stable cell lines were selected as described above.

[0225] α_(1B) Human Adrenergic Receptor: The entire coding region ofα_(1B) (1563 bp), including 200 basepairs and 5′ untranslated sequence(3′ UT) and 600 bp of 3′ untranslated sequence (3′ UT), was cloned intothe EcoRI site of pCEXV-3 eukaryotic expression vector (Bard et al,International Publication No. WO 94/08040, published Apr. 14, 1994). Theconstruct involved ligating the full-length containing EcoRI brainstemcDNA fragment from ZapII into the expression vector. The stable celllines were selected as described above.

[0226] α_(1C) Human Adrenergic Receptor: The entire coding region ofα_(1C) (1401 bp), including 400 basepairs of 5′ untranslated sequence(5′ UT) and 200 p of 3′ untranslated sequences (3′ UT), was cloned intothe KpnI site of the polylinker-modified pCEXV-3-derived eukaryoticexpression vector, EXJ.RH (Bard et al, International Publication No. WO94/08040, published Apr. 14, 1994). The construct involved ligationthree partial overlapping fragments: a 5′ 0.6 kb HincII genomic clone, acentral 1.8 EcoRI hippocampal cDNA clone, and a 3′ 0.6 Kb PstI genomicclone. The hippocampal cDNA fragment overlaps with the 5′ and 3′ genomicclones so that the HincII nad PstI sites at the 5′ and 3′ ends of thecDNA clone, respectively, were utilized for ligation. This full-lengthclone was cloned into the KpnI site of the expression vector, using the5′ and 3′ KpnI sites of the fragment, derived from vector (i.e.,pBluescript) and 3′-untranslated sequences, respectively. Stable celllines were selected as described above. TABLE 1 Binding and FunctionalActivities at Cloned Human Alpha-Adrenergic Receptors Alpha-2 Alpha-1 ExA B C A B C 1 pKi 7.74 7.13 7.15 5.17 4.61 5.28 pEC50 7.24 7.35 8.56 I.A1.00 1.00 1.00 2 pKi 8.41 7.69 7.01 6.02 5.23 5.77 pEC50 9.53 7.73 8.93I.A 1.00 1.00 1.00 3 pKi 8.12 7.81 7.00 6.27 5.09 5.72 pEC50 9.18 7.909.25 I.A 1.00 1.00 1.00 4 pKi 8.51 8.04 7.59 6.22 5.56 6.14 pEC50 9.418.01 9.45 I.A 1.00 1.00 1.00 5 pKi 8.45 7.51 7.62 6.27 5.74 5.65 pEC509.05 7.33 8.87 I.A 1.00 1.00 1.00 6 pKi 8.33 7.65 7.32 ND ND ND pEC508.17 7.65 8.40 I.A 1.00 1.00 1.00 7 pKi 8.45 7.55 7.38 6.57 5.91 5.75pEC50 8.14 6.70 8.21 I.A 1.00 1.00 1.00 8 pKi 7.59 7.30 6.92 6.17 5.585.75 pEC50 6.87 6.63 7.68 I.A 0.90 0.80 1.00 9 pKi 7.74 7.33 6.81 5.564.87 5.17 pEC50 6.65 7.23 7.92 I.A 1.00 1.00 1.00 10 pKi 8.23 7.55 7.816.21 5.42 6.07 pEC50 8.52 6.99 8.63 I.A 1.00 1.00 1.00 11 pKi 7.09 6.655.95 5.00 4.45 5.24 pEC50 NA NA NA I.A 12 pKi 8.20 7.84 7.59 7.02 6.466.46 pEC50 7.27 7.51 7.76 I.A 1.00 1.00 1.00 13 pKi 7.85 6.44 6.40 4.984.03 5.53 pEC50 NA NA NA I.A 14 pKi 8.02 6.66 6.64 5.63 4.69 6.21 pEC506.60 NA NA I.A 1.00 15 pKi 6.94 6.14 6.06 5.19 4.46 5.31 pEC50 NA NA NAI.A 16 pKi 8.25 7.91 7.38 7.26 6.29 6.38 pEC50 6.40 NA NA I.A 1.00 17pKi 7.39 6.18 6.08 4.98 4.35 5.04 pEC50 NA NA NA I.A 1.00 18 pKi 8.356.43 6.55 5.57 4.70 6.05 pEC50 7.08 NA NA I.A 0.80 19 pKi 8.33 6.67 6.89ND ND ND pEC50 6.31 NA NA I.A 0.70 20 pKi 6.62 6.14 6.20 4.83 4.23 4.95pEC50 NA NA NA I.A 21 pKi 8.19 7.67 7.26 6.13 5.33 5.92 pEC50 6.60 NA NAI.A 0.90 22 pKi 8.10 6.37 6.74 4.98 3.98 5.73 pEC50 NA NA NA I.A 23 pKi7.90 6.51 6.64 5.30 4.42 6.42 pEC50 6.16 NA NA I.A 0.90 24 pKi 8.48 7.897.47 6.51 5.31 6.60 pEC50 7.34 NA NA I.A 1.00 25 pKi 7.79 6.19 6.36 5.214.35 5.01 pEC50 NA NA NA I.A 26 pKi 7.93 6.25 6.59 5.05 4.24 5.02 pEC50NA NA NA I.A 27 pKi 7.03 5.99 6.14 5.08 4.47 5.16 pEC50 NA NA NA I.A 28pKi 8.41 7.38 7.02 6.18 4.98 5.42 pEC50 NA NA NA I.A 29 pKi 7.58 6.446.31 6.04 4.68 5.85 pEC50 NA NA NA I.A 30 pKi 7.76 6.78 6.51 ND ND NDpEC50 NA NA NA I.A 31 pKi 8.18 7.43 7.41 6.59 5.67 6.43 pEC50 NA NA NAI.A 32 pKi 7.96 7.30 6.79 5.43 4.48 5.41 pEC50 NA NA NA I.A 33 pKi 8.477.86 6.79 5.74 4.48 5.84 pEC50 NA NA NA I.A 34 pKi 7.42 7.05 6.73 5.594.92 5.87 pEC50 NA NA NA I.A 35 pKi 8.46 7.80 7.77 6.51 5.71 6.10 pEC50NA NA NA I.A 36 pKi 8.02 6.97 6.78 6.09 4.96 5.19 pEC50 8.26 6.55 NA I.A0.60 0.60 37 pKi 8.18 7.09 6.93 ND ND ND pEC50 7.69 NA 7.28 I.A 0.600.50 38 pKi 7.41 6.28 5.89 5.14 4.76 5.17 pEC50 7.45 6.80 6.44 I.A 1.000.80 1.00 39 pKi 7.36 6.31 6.21 5.80 4.96 5.3~ pEC50 7.61 NA NA I.A 0.9040 pKi 6.40 6.02 5.55 5.03 4.57 5.04 pEC50 6.14 NA NA I.A 0.80 42 pKi7.99 7.63 6.67 5.79 5.07 5.09 pEC50 7.63 7.01 NA I.A 1.00 0.60 43 pKi8.14 7.47 6.74 5.76 5.16 5.67 pEC50 7.64 6.79 7.09 I.A 1.00 0.80 0.90 44pKi 8.53 7.33 6.67 5.69 5.23 5.51 pEC50 8.40 7.04 6.74 I.A 1.00 0.800.80 45 pKi 8.07 7.08 6.53 5.34 4.94 5.66 pEC50 7.28 6.07 7.92 I.A 1.000.70 0.60 46 pKi 7.34 6.98 5.83 5.15 4.55 4.97 pEC50 7.41 6.23 7.19 I.A1.00 0.80 0.90 47 pKi 8.17 7.35 6.65 ND ND ND pEC50 7.33 6.94 7.34 I.A1.00 0.80 0.80 48 pKi 7.11 6.18 6.62. 5.91 7.31 6.92 pEC50 NA 6.70 8.87I.A 0.80 0.60 49 pKi 7.71 7.44 6.67 ND ND ND pEC50 7.04 NA 7.65 I.A 0.801.00 50 pKi 8.16 8.63 7.61 7.45 6.78 6.11 pEC50 7.80 7.68 7.15 I.A 1.000.90 1.00 51 pKi 7.58 7.56 6.91 ND ND ND pEC50 7.01 7.05 8.37 I.A 0.900.60 1.00 52 pKi 7.61 7.11 6.90 ND ND ND pEC50 7.09 7.14 8.26 I.A 0.900.80 1.00 53 pKi 7.83 7.74 7.05 6.51 5.72 6.00 pEC50 7.24 7.74 8.97 I.A1.00 1.00 1.00 54 pKi 7.31 7.56 6.70 ND ND ND pEC50 5.90 6.88 7.69 I.A0.70 0.60 0.90 55 pKi 7.36 6.68 6.37 ND ND ND pEC50 7.29 NA 6.79 I.A0.60 0.80 56 pKi 7.66 6.74 6.69 5.90 5.29 6.23 pEC50 6.30 6.86 7.89 I.A0.70 0.30 1.00 57 pKi 7.78 7.22 6.87 ND ND ND pEC50 NA 5.07 7.82 I.A0.50 1.00 58 pKi 8.89 8.76 7.51 ND ND ND pEC50 8.61 7.55 8.49 I.A 1.000.50 1.00 59 pKi 9.01 8.10 7.78 ND ND ND pEC50 9.08 7.39 8.89 I.A 1.000.90 1.00 60 pKi 9.05 9.33 7.79 6.85 6.5  6.32 pEC50 9.23 7.75 9.4  I.A1   0.9  1   C pKi 8.03 8.09 7.52 6.29 5.62 6.01 pEC50 8.09 6.79 7.26I.A 1   1   1  

[0227] The protocols used to obtain these data are described in Example61.

EXAMPLE 62

[0228] Assay to Measure Analgesic Activity of Test Compounds

[0229] Warm-Water Tail Withdrawal Assay (Butelman, E. R.; Woods, J. H.J. Pharmacol. Exp. Therapeut. 1993, 264, 7620)

[0230] Subjects. Adult rhesus monkeys (Macaca mulatta) of either sexwere housed individually with free access to water. They were fed freshfruit weekly and approximately 40 biscuits (Purina Monkey Chow) daily.

[0231] Apparatus and procedure. Tail withdrawal latencies were timedmanually using a microprocessor (IBM PCjr) via a push button switch.Monkeys were seated in primate restraining chairs, and the lower portionof the shaved tail (approximately 10 cm) was immersed in a thermos flaskcontaining water maintained at either 40, 50 or 55° C. A maximum allowedlatency of 20 seconds was recorded if the monkeys failed to remove theirtails by this time. Sessions began with control determinations at eachwater temperature, presented in a varied order between the subjects. Inorder for a subject to be used, its withdrawal latency at 40° C. had toreach 20 seconds. After control determinations, drugs were administeredevery 30 minutes using a cumulative dosing procedure in which dosesincreased in 0.25 or 0.5 log units with each cycle. Fifteen minutesafter each injection, the subjects were tested at the three temperaturesin varying order, with tests being separated from each other byapproximately 2 minutes. In time course studies, a single drug dose wasadministered after control determination, with testing following at 30minute intervals.

[0232] Design. Clonidine and compound 4 were studied up to doses thatproduced near maximal withdrawal latencies in 55° C. water. The samethree subjects were studied in all the above experiments.

[0233] Sedation and Muscle Relaxation.

[0234] Procedure. Monkeys were trained to receive subcutaneousinjections while in their home cages; they were rated by one non-blindobserver familiar with the individual subjects, according to modifiedrating scales for sedation and muscle relaxation (Table 2). Separatescales describe increasing degrees of sedation (as measured byresponsiveness to stimuli) and muscle relaxation (as observed throughchanges in posture). Animals were injected in a cumulative dosingprocedure with a 30 minute interinjection interval; observer rating onboth scales took place approximately 15 minutes after each injection.

[0235] Design. Clonidine (0.032-1.0 mg/kg) and compound 4 (0.1-3.2mg/kg) were studied using a cumulative dosing procedure. The same threemonkeys were typically studied under each se of conditions.

[0236] Results: Using the procedures described above, compound 4 wasfound to be an effective analgesic agent with decreased sedationrelative to the reference compound, clonidine. TABLE 2 Modified sedationand muscle relaxation rating scales Grade Sedation 0 No observablesedation 1 Monkey appears to stare into space 2 Monkey is inattentive toordinary movements of observer 3 Monkey responds only to loud noises inthe room 4 Monkey responds only to opening of cage latch 5 Monkeyresponds only to loud noises near its ear 6 Monkey responds only totouch Muscle Relaxation 0 No observable muscle relaxation 1 Slightfacial relaxation, jaw slackening, shoulder droop 2 Pronounced facialrelaxation, jaw slackening, shoulder droop 3 Monkey must brace itself tosit up 4 Monkey cannot sit up

What is claimed is:
 1. A compound having the structure:

wherein each of R₁, R₂, R₃ and R₉ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; wherein each dashed line represents a single bondor a double bond with the proviso that if R₁ is present, R₃ is absentand there is a double bond between N at position 3 and C at position 2and a single bond between C at position 2 and N at position 1 and if R₃is present, R₁ is absent and there is a double bond between N atposition 1 and C at position 2 and a single bond between C at position 2and N at position 3; wherein each of R₄, R₁ and R₆ is independently H,F, Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4; and wherein each of R₇ and R₈ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; phenyl or substituted phenyl.
 2. A compound having thestructure:

wherein each of R₁, R₂ and R₃ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; and wherein each of R₄ and R₆ is independently H,F, Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4.
 3. The compound of claim 1, wherein R₄ is H.
 4. The compound of claim1, wherein R₄ is Br.
 5. The compound of claim 1, wherein R₄ is Cl. 6.The compound of claim 1, wherein R₄ is CH₃.
 7. The compound of claim 1,wherein R₆ is Cl.
 8. The compound of claim 1, wherein R₆ is CH₃.
 9. Thecompound of claim 1, wherein R₄ is Br and R₆ is Cl.
 10. The compound ofclaim 1, wherein R₄ and R₆ are both Cl.
 11. The compound of claim 1,wherein R₁ is CH(CH₃)₂ and R₄ is Br.
 12. The compound of claim 1,wherein R₂ is CH(CH₃)₂ and R₄ is Br.
 13. The compound of claim 1 havingthe structure:


14. The compound of claim 1 having the structure:


15. The compound of claim 1 having the structure:


16. The compound of claim 1 having the structure:


17. The compound of claim 1 having the structure:


18. The compound of claim 1 having the structure:


19. The compound of claim 1 having the structure:


20. The compound of claim 1 having the structure:


21. The compound of claim 1 having the structure:


22. The compound of claim 1 having the structure:


23. A pharmaceutical composition comprising a therapeutically effectiveamount of the compound of claims 1 or 2 and a pharmaceuticallyacceptable carrier.
 24. A method for treating an alpha-2 adrenergicreceptor associated disorder in a subject which comprises administeringto the subject an amount of a compound having the structure:

wherein each of R₁, R₂, R₃ and R₉ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; wherein each dashed line represents a single bondor a double bond with the proviso that if R₁ is present, R₃ is absentand there is a double bond between N at position 1 and and C at position2 and a single bond between C at position 2 and N at position 3 and ifR₃ is present, R₁ is absent and there is a double bond between N atposition 3 and C at position 2 and a single bond between C at position 2and N at position 1; wherein each of R₄, R₅ and R₆ is independently H,F, Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4; and wherein each of R₇ and R₈ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; phenyl or substituted phenyl.
 25. The method of claim 24,wherein the compound administered to the subject has the structure:

wherein each of R₁, R₂ and R₃ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; wherein each of R₄ and R₆ is independently H, F,Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4.
 26. A method for alleviating pain in a subject which comprisesadministering to the subject an amount of a compound having thestructure:

wherein each of R₁, R₂, R₃ and R₉ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; wherein each dashed line represents a single bondor a double bond with the proviso that if R₁ is present, R₃ is absentand there is a double bond between N at position 1 and and C at position2 and a single bond between C at position 2 and N at position 3 and ifR₃ is present, R₁ is absent and there is a double bond between N atposition 3 and C at position 2 and a single bond between C at position 2and N at position 1; wherein each of R₄, R₅ and R₆ is independently H,F, Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇,)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4; and wherein each of R₇ and R₈ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; phenyl or substituted phenyl.
 27. The method of claim 26,wherein the compound administered to the subject has the structure:

wherein each of R₁, R₂ and R₃ is independently H; straight chain orbranched, substituted or unsubstituted C₁-C₇ alkyl, C₂-C₇ alkenyl oralkynyl; C₃-C₇ cycloalkyl or cycloalkenyl; acyl, phenyl, substitutedphenyl, or heteroaryl; wherein each of R₄ and R₆ is independently H, F,Cl, Br, I; straight chain or branched, substituted or unsubstitutedC₁-C₇ alkyl, C₂-C₇ alkenyl or alkynyl; C₃-C₇ cycloalkyl or cycloalkenyl;phenyl, substituted phenyl, heteroaryl, —OH, —OR₇, —CN, —COR₇, —CO₂R₇,—CON(R₇)₂, —OCOR₇, —SR₇, —N(R₇)₂, —NR₇COR₇, —(CH₂)_(n)OR₇,—(CH₂)_(n)N(R₇)₂, —(CH₂)_(n)NR₇COR₇, wherein n is an integer from 1 to4.
 28. The method of claim 27, wherein the compound administered to thesubject has the structure: